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Lv L, Li S, Kang J, Li Y, Zhao N, Ye D, Qin F, Sun J, Yu T, Wu H. Inhibition of ABI2 ubiquitination-dependent degradation suppresses TNBC cell growth via down-regulating PI3K/Akt signaling pathway. Cancer Cell Int 2024; 24:222. [PMID: 38937761 PMCID: PMC11212232 DOI: 10.1186/s12935-024-03407-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Accepted: 06/19/2024] [Indexed: 06/29/2024] Open
Abstract
Triple negative breast cancer (TNBC) is a type of cancer that lacks receptor expression and has complex molecular mechanisms. Recent evidence shows that the ubiquitin-protease system is closely related to TNBC. In this study, we obtain a key ubiquitination regulatory substrate-ABI2 protein by bioinformatics methods, which is also closely related to the survival and prognosis of TNBC. Further, through a series of experiments, we demonstrated that ABI2 expressed at a low level in TNBC tumors, and it has the ability to control cell cycle and inhibit TNBC cell migration, invasion and proliferation. Molecular mechanism studies proved E3 ligase CBLC could increase the ubiquitination degradation of ABI2 protein. Meanwhile, RNA-seq and IP experiments indicated that ABI2, acting as a crucial factor of tumor suppression, can significantly inhibit PI3K/Akt signaling pathway via the interaction with Rho GTPase RAC1. Finally, based on TNBC drug target ABI2, we screened and found that FDA-approved drug Colistimethate sodium(CS) has significant potential in suppressing the proliferation of TNBC cells and inducing cell apoptosis, making it a promising candidate for impeding the progression of TNBC.
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Affiliation(s)
- Linlin Lv
- School of Bioengineering & Key Laboratory of Protein Modification and Disease, Dalian University of Technology, Dalian, Liaoning Province, 116024, China
- Department of Pharmacy, First Affiliated Hospital of Dalian Medical University, Dalian, Liaoning, China
| | - Shujing Li
- School of Bioengineering & Key Laboratory of Protein Modification and Disease, Dalian University of Technology, Dalian, Liaoning Province, 116024, China
| | - Jie Kang
- School of Bioengineering & Key Laboratory of Protein Modification and Disease, Dalian University of Technology, Dalian, Liaoning Province, 116024, China
| | - Yulin Li
- School of Bioengineering & Key Laboratory of Protein Modification and Disease, Dalian University of Technology, Dalian, Liaoning Province, 116024, China
| | - Nannan Zhao
- Cancer Hospital of Dalian University of Technology, Shenyang, 110042, China
| | - Dongman Ye
- Cancer Hospital of Dalian University of Technology, Shenyang, 110042, China
| | - Fengying Qin
- Cancer Hospital of Dalian University of Technology, Shenyang, 110042, China
| | - Jing Sun
- Cancer Hospital of Dalian University of Technology, Shenyang, 110042, China.
| | - Tao Yu
- Cancer Hospital of Dalian University of Technology, Shenyang, 110042, China.
| | - Huijian Wu
- School of Bioengineering & Key Laboratory of Protein Modification and Disease, Dalian University of Technology, Dalian, Liaoning Province, 116024, China.
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Li K, You G, Jiang K, Wang R, Li W, Meng Y, Fang Y, Chen W, Zhu G, Song J, Wang W, Su H, Hu B, Sun F, Jia Z, Li C, Zhu J. Root extract of Hemsleya amabilis Diels suppresses renal cell carcinoma cell growth through inducing apoptosis and G 2/M phase arrest via PI3K/AKT signaling pathway. JOURNAL OF ETHNOPHARMACOLOGY 2024; 318:117014. [PMID: 37557938 DOI: 10.1016/j.jep.2023.117014] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 06/16/2023] [Accepted: 08/07/2023] [Indexed: 08/11/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Hemsleya amabilis Diels, belongs to cucurbitaceae, was traditional Chinese medicine (TCM). It is widely used to treat various diseases. However, these diseases may contribute to the development of RCC. AIM OF THE STUDY investigated the anticancer activities of root extract of Hemsleya amabilis Diels (HRE), and elucidated the underlying molecular mechanism in vivo and in vitro. MATERIALS AND METHODS Dried Hemsleya amabilis Diels roots were extracted by ethyl acetate and used to treat RCC4, OS-RC-2 and ACHN cells. UHPLC-MS was used to analyze the chemical composition of the extract. CCK-8 and colony formation assay were used to investigate proliferation. PI staining was used to detect cell cycle. Annexin-V-FITC, AO/EB and TEM were used to evaluate apoptosis. Transwell and wound healing assays were used to evaluate migration and invasion. RNA-seq, Network pharmacology, autodocking for virtual screening and molecular dynamics simulation were used to analyze potential molecular mechanisms and active components of HRE inhibiting proliferation of RCC. LY294002 and UC2288 were used to inhibit PI3K and P21 expression, respectively. IGF-1 was used to activate PI3K. Xenograft tumor model was established to evaluate its anti-tumor potential in vivo. Immunohistochemistry and Western blot were used to test protein expression levels. H&E staining was used to explore the side effects of HRE in vivo. Applying bioinformatics to analyze the effect of P21 on RCC. RESULTS HRE consists of 739 compounds. CCK-8 and colony formation assay showed that HRE significantly inhibited RCC cells proliferation. PI staining indicated that HRE caused G2/M phase arrest. Annexin-V-FITC, AO/EB and TEM experiments revealed that HRE significantly promoted apoptosis of RCC cells. Transwell and wound healing assays showed that HRE can inhibit the migration and invasion of RCC cells. RNA-seq showed that HRE induced 230 gene changes. Network pharmacology analysis found the relationship between HRE-component-target-RCC. Auto-docking found that Epitulipinolide diepoxide in HRE can stably bind to PIK3CA (-7.22 kJ/mol), and molecular dynamics simulation verified the combination between Epitulipinolide diepoxide of PIK3CA. In RCC4 cells, pretreatment with IGF-1, attenuated HRE-induced apoptosis and G2/M arrest. When pretreated with PIK3 inhibitor LY294002, the opposite result appears. Pretreatment with CDKN1A (P21) inhibitor UC2288 attenuated HRE-induced G2/M arrest. Xenograft tumor model showed that HRE inhibited tumor growth. Western blot analysis indicated that HRE can regulating Bax, Bcl-2, PARP, cleared-PARP, Caspase-9, Caspase-8, Caspase-3, Survivin, Cyclin-B1, CDK1, N-cadherin, snail, slug, E-cadherin, MMP-9. Immunohistochemical staining showed that in the treated group, expression of E-cadherin, Bax, P21 was up-regulated, while N-cadherin, PI3K, AKT and Bcl-2 were down-regulated. H&E staining showed that compared to control groups, the main organs in the HRE-treated groups showed no histological abnormalities. The overall survival rate of RCC patients in the high-expression group of P21 was higher than in the low-expression group of P21 on bioinformatics analysis. CONCLUSIONS HRE inhibited RCC migration and invasion through EMT, and inhibited proliferation in vivo and in vitro. In addition, HRE inhibited proliferation through promoting apoptosis and P21-induced G2/M phase arrest via PI3K/AKT signaling pathway. Overall, these results suggest that HRE may be a promising chemotherapy agent for RCC.
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Affiliation(s)
- Kai Li
- Guizhou Provincial Key Laboratory for Rare Animal and Economic Insect of the Mountainous Region, College of Biology and Environmental Engineering, Guiyang University, Guiyang, 550025, China
| | - Ganhua You
- The Second People's Hospital of Guizhou Province, Guiyang, 550002, China
| | - Kehua Jiang
- Department of Urology, Guizhou Provincial People's Hospital, The Affiliated Hospital of Guizhou Medical University, Guiyang, Guizhou Province, 550002, China
| | - Rongpin Wang
- Department of Radiology, Guizhou Provincial People's Hospital, Guiyang, Guizhou, 550002, China
| | - Wuchao Li
- Department of Radiology, Guizhou Provincial People's Hospital, Guiyang, Guizhou, 550002, China
| | - Yonglu Meng
- Guizhou Provincial Key Laboratory for Rare Animal and Economic Insect of the Mountainous Region, College of Biology and Environmental Engineering, Guiyang University, Guiyang, 550025, China
| | - Yinyi Fang
- Medical College of Guizhou University, Guiyang, Guizhou Province, 550025, China
| | - Weiming Chen
- Medical College of Guizhou University, Guiyang, Guizhou Province, 550025, China
| | - Guohua Zhu
- Department of Pedictric, Guizhou Provincial People's Hospital, The Affiliated Hospital of Guizhou Medical University, Guiyang, Guizhou Province, 550002, China
| | - Jukun Song
- Department of Oral and Maxillofacial Surgery, The Affiliated Stomatological Hospital of Guizhou Medical University, Guiyang, China
| | - Wei Wang
- Department of Pedictric, Guizhou Provincial People's Hospital, The Affiliated Hospital of Guizhou Medical University, Guiyang, Guizhou Province, 550002, China
| | - Hao Su
- Department of Urology, Guizhou Provincial People's Hospital, The Affiliated Hospital of Guizhou Medical University, Guiyang, Guizhou Province, 550002, China
| | - Bin Hu
- Department of Urology, Kweichow Moutai Hospital, Renhuai, China
| | - Fa Sun
- Department of Urology, Guizhou Provincial People's Hospital, The Affiliated Hospital of Guizhou Medical University, Guiyang, Guizhou Province, 550002, China.
| | - Zhenyu Jia
- University of California of Riverside, Riverside, CA, 92521, USA.
| | - Can Li
- Guizhou Provincial Key Laboratory for Rare Animal and Economic Insect of the Mountainous Region, College of Biology and Environmental Engineering, Guiyang University, Guiyang, 550025, China.
| | - Jianguo Zhu
- Guizhou Provincial Key Laboratory for Rare Animal and Economic Insect of the Mountainous Region, College of Biology and Environmental Engineering, Guiyang University, Guiyang, 550025, China; Department of Urology, Guizhou Provincial People's Hospital, The Affiliated Hospital of Guizhou Medical University, Guiyang, Guizhou Province, 550002, China.
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Wu W, Xia X, Tang L, Luo J, Xiong S, Ma G, Lei H. Phosphoinositide 3-kinase as a therapeutic target in angiogenic disease. Exp Eye Res 2023; 236:109646. [PMID: 37716399 DOI: 10.1016/j.exer.2023.109646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 08/30/2023] [Accepted: 09/05/2023] [Indexed: 09/18/2023]
Abstract
Phosphoinositide 3-kinases (PI3Ks) generate lipids that control multitudinous intracellular cell signaling events which participate in cell survival and proliferation. In addition, PI3K signaling also contributes to metabolism, immunity, angiogenesis and cardiovascular homeostasis, and many diseases. The diverse actions of PI3K stem from the existence of their various isoforms and a variety of protein effectors. Hence, PI3K isoform-specific inhibitors have already achieved a wonderful effect on treating cancer. Herein, we summarize the molecular mechanism of PI3K inhibitors in preventing the permeability of vessels and neovascularization. Additionally, we briefly illustrate how PI3K signaling modulates blood vessel growth and discuss the different roles that PI3K isoforms play in angiogenesis.
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Affiliation(s)
- Wenyi Wu
- Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, China; Hunan Key Laboratory of Ophthalmology, Changsha, China; National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China.
| | - Xiaobo Xia
- Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, China; Hunan Key Laboratory of Ophthalmology, Changsha, China; National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Luosheng Tang
- Department of Ophthalmology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Jing Luo
- Department of Ophthalmology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Siqi Xiong
- Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, China; Hunan Key Laboratory of Ophthalmology, Changsha, China; National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Gaoen Ma
- Department of Ophthalmology, The First Affiliated Hospital of Hainan Medical University, Haikou, 571199, China.
| | - Hetian Lei
- Shenzhen Eye Hospital, Jinan University, Shenzhen Eye Institute, Shenzhen, China.
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Roads to Stat3 Paved with Cadherins. Cells 2022; 11:cells11162537. [PMID: 36010614 PMCID: PMC9406956 DOI: 10.3390/cells11162537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 08/01/2022] [Accepted: 08/09/2022] [Indexed: 11/17/2022] Open
Abstract
The engagement of cadherins, cell-to-cell adhesion proteins, triggers a dramatic increase in the levels and activity of the Rac/Cdc42 GTPases, through the inhibition of proteasomal degradation. This leads to an increase in transcription and secretion of IL6 family cytokines, activation of their common receptor, gp130, in an autocrine manner and phosphorylation of the signal transducer and activator of transcription-3 (Stat3) on tyrosine-705 by the Jak kinases. Stat3 subsequently dimerizes, migrates to the nucleus and activates the transcription of genes involved in cell division and survival. The Src oncogene also increases Rac levels, leading to secretion of IL6 family cytokines and gp130 activation, which triggers a Stat3-ptyr705 increase. Interestingly, at the same time, Src downregulates cadherins in a quantitative manner, while cadherins are required to preserve gp130 levels for IL6 family signalling. Therefore, a fine balance between Src527F/Rac/IL6 and Src527F/cadherin/gp130 levels is in existence, which is required for Stat3 activation. This further demonstrates the important role of cadherins in the activation of Stat3, through preservation of gp130 function. Conversely, the absence of cadherin engagement correlates with low Stat3 activity: In sparsely growing cells, both gp130 and Stat3-ptyr705 levels are very low, despite the fact that cSrc is active in the FAK (focal adhesion kinase)/cSrc complex, which further indicates that the engagement of cadherins is important for Stat3 activation, not just their presence. Furthermore, the caveolin-1 protein downregulates Stat3 through binding and sequestration of cadherins to the scaffolding domain of caveolin-1. We hypothesize that the cadherins/Rac/gp130 axis may be a conserved pathway to Stat3 activation in a number of systems. This fact could have significant implications in Stat3 biology, as well as in drug testing and development.
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Development of New Drugs for Autoimmune Hemolytic Anemia. Pharmaceutics 2022; 14:pharmaceutics14051035. [PMID: 35631621 PMCID: PMC9147507 DOI: 10.3390/pharmaceutics14051035] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 04/27/2022] [Accepted: 05/05/2022] [Indexed: 02/04/2023] Open
Abstract
Autoimmune hemolytic anemia (AIHA) is a rare disorder characterized by the autoantibody-mediated destruction of red blood cells, and treatments for it still remain challenging. Traditional first-line immunosuppressive therapy, which includes corticosteroids and rituximab, is associated with adverse effects as well as treatment failures, and relapses are common. Subsequent lines of therapy are associated with higher rates of toxicity, and some patients remain refractory to currently available treatments. Novel therapies have become promising for this vulnerable population. In this review, we will discuss the mechanism of action, existing data, and ongoing clinical trials of current novel therapies for AIHA, including B-cell-directed therapy, phagocytosis inhibition, plasma cell-directed therapy, and complement inhibition.
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6
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Ratti S, Mauro R, Rocchi C, Mongiorgi S, Ramazzotti G, Gargiulo M, Manzoli L, Cocco L, Fiume R. Roles of PI3K/AKT/mTOR Axis in Arteriovenous Fistula. Biomolecules 2022; 12:biom12030350. [PMID: 35327539 PMCID: PMC8945685 DOI: 10.3390/biom12030350] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 01/28/2022] [Accepted: 02/14/2022] [Indexed: 11/22/2022] Open
Abstract
Renal failure is a worldwide disease with a continuously increasing prevalence and involving a rising need for long-term treatment, mainly by haemodialysis. Arteriovenous fistula (AVF) is the favourite type of vascular access for haemodialysis; however, the lasting success of this therapy depends on its maturation, which is directly influenced by many concomitant processes such as vein wall thickening or inflammation. Understanding the molecular mechanisms that drive AVF maturation and failure can highlight new or combinatorial drugs for more personalized therapy. In this review we analysed the relevance of critical enzymes such as PI3K, AKT and mTOR in processes such as wall thickening remodelling, immune system activation and inflammation reduction. We focused on these enzymes due to their involvement in the modulation of numerous cellular activities such as proliferation, differentiation and motility, and their impairment is related to many diseases such as cancer, metabolic syndrome and neurodegenerative disorders. In addition, these enzymes are highly druggable targets, with several inhibitors already being used in patient treatment for cancer and with encouraging results for AVF. Finally, we delineate how these enzymes may be targeted to control specific aspects of AVF in an effort to propose a more specialized therapy with fewer side effects.
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Affiliation(s)
- Stefano Ratti
- Cellular Signalling Laboratory, Department of Biomedical and Neuromotor Sciences, University of Bologna, 40126 Bologna, Italy; (S.R.); (S.M.); (G.R.); (L.M.); (R.F.)
| | - Raffaella Mauro
- Vascular Surgery Unit, IRCCS University Hospital, Policlinico S. Orsola-Malpighi, 40126 Bologna, Italy; (R.M.); (C.R.); (M.G.)
| | - Cristina Rocchi
- Vascular Surgery Unit, IRCCS University Hospital, Policlinico S. Orsola-Malpighi, 40126 Bologna, Italy; (R.M.); (C.R.); (M.G.)
| | - Sara Mongiorgi
- Cellular Signalling Laboratory, Department of Biomedical and Neuromotor Sciences, University of Bologna, 40126 Bologna, Italy; (S.R.); (S.M.); (G.R.); (L.M.); (R.F.)
| | - Giulia Ramazzotti
- Cellular Signalling Laboratory, Department of Biomedical and Neuromotor Sciences, University of Bologna, 40126 Bologna, Italy; (S.R.); (S.M.); (G.R.); (L.M.); (R.F.)
| | - Mauro Gargiulo
- Vascular Surgery Unit, IRCCS University Hospital, Policlinico S. Orsola-Malpighi, 40126 Bologna, Italy; (R.M.); (C.R.); (M.G.)
| | - Lucia Manzoli
- Cellular Signalling Laboratory, Department of Biomedical and Neuromotor Sciences, University of Bologna, 40126 Bologna, Italy; (S.R.); (S.M.); (G.R.); (L.M.); (R.F.)
| | - Lucio Cocco
- Cellular Signalling Laboratory, Department of Biomedical and Neuromotor Sciences, University of Bologna, 40126 Bologna, Italy; (S.R.); (S.M.); (G.R.); (L.M.); (R.F.)
- Correspondence: ; Tel.: +39-051-209-1639
| | - Roberta Fiume
- Cellular Signalling Laboratory, Department of Biomedical and Neuromotor Sciences, University of Bologna, 40126 Bologna, Italy; (S.R.); (S.M.); (G.R.); (L.M.); (R.F.)
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PI3K Isoforms in Vascular Biology, A Focus on the Vascular System-Immune Response Connection. Curr Top Microbiol Immunol 2022; 436:289-309. [DOI: 10.1007/978-3-031-06566-8_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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8
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Class I PI3K Biology. Curr Top Microbiol Immunol 2022; 436:3-49. [DOI: 10.1007/978-3-031-06566-8_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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9
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Borsari C, Wymann MP. Targeting Phosphoinositide 3-Kinase - Five Decades of Chemical Space Exploration. Chimia (Aarau) 2021; 75:1037-1044. [PMID: 34920774 DOI: 10.2533/chimia.2021.1037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Phosphoinositide 3-kinase (PI3K) plays a key role in a plethora of physiologic processes and controls cell growth, metabolism, immunity, cardiovascular and neurological function, and more. The discovery of wort-mannin as the first potent PI3K inhibitor (PI3Ki) in the 1990s provided rapid identification of PI3K-dependent processes, which drove the discovery of the PI3K/protein kinase B (PKB/Akt)/target of rapamycin (mTOR) pathway. Genetic mouse models and first PI3K isoform-specific inhibitors pinpointed putative therapeutic applications. The recognition of PI3K as target for cancer therapy drove subsequently drug development. Here we provide a brief journey through the emerging roles of PI3K to the development of preclinical and clinical PI3Ki candidates.
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Affiliation(s)
- Chiara Borsari
- Department of Biomedicine, University of Basel, Mattenstrasse 28, CH-4058 Basel, Switzerland
| | - Matthias P Wymann
- Department of Biomedicine, University of Basel, Mattenstrasse 28, CH-4058 Basel, Switzerland;,
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10
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Fardi Golyan F, Forghanifard MM. A new gene panel as a marker for ESCC poor prognosis; INPP5A, TWIST1, MMP2, and EGFR. Adv Med Sci 2021; 66:231-236. [PMID: 33798953 DOI: 10.1016/j.advms.2021.03.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 01/29/2021] [Accepted: 03/12/2021] [Indexed: 01/09/2023]
Abstract
PURPOSE Esophageal squamous cell carcinoma (ESCC) is categorized among ten common aggressive malignancies, with a higher incidence and mortality rates in the developing than in developed countries. The inositol polyphosphate 5-phosphatase (INPP5A), as an intracellular-calcium mobilizer and modifier enzyme, facilitates cell responses to various stimuli. Epithelial-mesenchymal transition (EMT), a transformation procedure, has a vital role in cancer progression and metastasis when epithelial cells lose their traits in favor of obtaining mesenchymal features. In this study, we analyzed the correlation between the expression of INPP5A and the involved genes in EMT pathway through the progression and development of the ESCCs. MATERIALS AND METHODS The gene expression analyses of INPP5A, TWIST1, MMP-2, and EGFR were performed using relative comparative real-time PCR in 58 ESCCs patients compared to corresponding margin-normal esophageal tissues. RESULTS A significant inverse correlation between INPP5A and EGFR/MMP-2 mRNA expression was observed in tumor samples. Underexpression of INPP5A was significantly correlated with overexpression of TWIST1, MMP-2, and EGFR in different invasiveness and aggressiveness pathological features of the ESCCs (P < 0.05). CONCLUSIONS The results propose a tumor suppressor role for INPP5A and oncogenic function for concomitant expression of the other genes in ESCC invasion and metastasis. The current study is the first report elucidating the correlation between the downregulation of INPP5A and upregulation of TWIST1, MMP-2, and EGFR in ESCC and introduces this panel of the genes as a marker for poor prognosis of the disease.
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Affiliation(s)
- Fatemeh Fardi Golyan
- Immunology Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
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11
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Abstract
The field of phosphoinositide signaling has expanded significantly in recent years. Phosphoinositides (also known as phosphatidylinositol phosphates or PIPs) are universal signaling molecules that directly interact with membrane proteins or with cytosolic proteins containing domains that directly bind phosphoinositides and are recruited to cell membranes. Through the activities of phosphoinositide kinases and phosphoinositide phosphatases, seven distinct phosphoinositide lipid molecules are formed from the parent molecule, phosphatidylinositol. PIP signals regulate a wide range of cellular functions, including cytoskeletal assembly, membrane budding and fusion, ciliogenesis, vesicular transport, and signal transduction. Given the many excellent reviews on phosphoinositide kinases, phosphoinositide phosphatases, and PIPs in general, in this review, we discuss recent studies and advances in PIP lipid signaling in the retina. We specifically focus on PIP lipids from vertebrate (e.g., bovine, rat, mouse, toad, and zebrafish) and invertebrate (e.g., Drosophila, horseshoe crab, and squid) retinas. We also discuss the importance of PIPs revealed from animal models and human diseases, and methods to study PIP levels both in vitro and in vivo. We propose that future studies should investigate the function and mechanism of activation of PIP-modifying enzymes/phosphatases and further unravel PIP regulation and function in the different cell types of the retina.
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Affiliation(s)
- Raju V S Rajala
- Departments of Ophthalmology, Physiology, and Cell Biology, and Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104.
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12
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p110δ PI3K as a therapeutic target of solid tumours. Clin Sci (Lond) 2020; 134:1377-1397. [DOI: 10.1042/cs20190772] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Revised: 05/21/2020] [Accepted: 06/01/2020] [Indexed: 12/12/2022]
Abstract
AbstractFrom the time of first characterization of PI3K as a heterodimer made up of a p110 catalytic subunit and a regulatory subunit, a wealth of evidence have placed the class IA PI3Ks at the forefront of drug development for the treatment of various diseases including cancer. The p110α isoform was quickly brought at the centre of attention in the field of cancer research by the discovery of cancer-specific gain-of-function mutations in PIK3CA gene in a range of human solid tumours. In contrast, p110δ PI3K was placed into the spotlight of immunity, inflammation and haematologic malignancies because of the preferential expression of this isoform in leucocytes and the rare mutations in PIK3CD gene. The last decade, however, several studies have provided evidence showing that the correlation between the PIK3CA mutations and the response to PI3K inhibition is less clear than originally considered, whereas concurrently an unexpected role of p110δ PI3K in solid tumours has being emerging. While PIK3CD is mostly non-mutated in cancer, the expression levels of p110δ protein seem to act as an intrinsic cancer-causing driver in various solid tumours including breast, prostate, colorectal and liver cancer, Merkel-Cell carcinoma, glioblastoma and neurobalstoma. Furthermore, p110δ selective inhibitors are being studied as potential single agent treatments or as combination partners in attempt to improve cancer immunotherapy, with both strategies to shown great promise for the treatment of several solid tumours. In this review, we discuss the evidence implicating the p110δ PI3K in human solid tumours, their impact on the current state of the field and the potential of using p110δ-selective inhibitors as monotherapy or combined therapy in different cancer contexts.
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13
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Simond AM, Muller WJ. In vivo modeling of the EGFR family in breast cancer progression and therapeutic approaches. Adv Cancer Res 2020; 147:189-228. [PMID: 32593401 DOI: 10.1016/bs.acr.2020.04.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Modeling breast cancer through the generation of genetically engineered mouse models (GEMMs) has become the gold standard in the study of human breast cancer. Notably, the in vivo modeling of the epidermal growth factor receptor (EGFR) family has been key to the development of therapeutics and has helped better understand the signaling pathways involved in cancer initiation, progression and metastasis. The HER2/ErbB2 receptor is a member of the EGFR family and 20% of breast cancers are found to belong in the HER2-positive histological subtype. Historical and more recent advances in the field have shaped our understanding of HER2-positive breast cancer signaling and therapeutic approaches.
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Affiliation(s)
- Alexandra M Simond
- Rosalind and Morris Goodman Cancer Research Center, McGill University, Montreal, QC, Canada; Department of Biochemistry, McGill University, Montreal, QC, Canada
| | - William J Muller
- Rosalind and Morris Goodman Cancer Research Center, McGill University, Montreal, QC, Canada; Department of Biochemistry, McGill University, Montreal, QC, Canada; Faculty of Medicine, McGill University, Montreal, QC, Canada.
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Neumann CKA, Silver DJ, Venkateshwari V, Zhang R, Traughber CA, Przybycin C, Bayik D, Smith JD, Lathia JD, Rini BI, Brown JM. MBOAT7-driven phosphatidylinositol remodeling promotes the progression of clear cell renal carcinoma. Mol Metab 2020; 34:136-145. [PMID: 32180553 PMCID: PMC7033598 DOI: 10.1016/j.molmet.2020.01.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 01/21/2020] [Indexed: 12/28/2022] Open
Abstract
Objective The most common kidney cancer, clear cell renal cell carcinoma (ccRCC), is closely associated with obesity. The “clear cell” variant of RCC gets its name from the large lipid droplets that accumulate in the tumor cells. Although renal lipid metabolism is altered in ccRCC, the mechanisms and lipids driving this are not well understood. Methods We used shotgun lipidomics in human ccRCC tumors and matched normal adjacent renal tissue. To assess MBOAT7s gene expression across tumor severity, we examined histologically graded human ccRCC samples. We then utilized genome editing in ccRCC cell lines to understand the role of MBOAT7 in ccRCC progression. Results We identified a lipid signature for ccRCC that includes an increase in arachidonic acid-enriched phosphatidylinositols (AA-PI). In parallel, we found that ccRCC tumors have increased expression of acyltransferase enzyme membrane bound O-acyltransferase domain containing 7 (MBOAT7) that contributes to AA-PI synthesis. In ccRCC patients, MBOAT7 expression increases with tumor grade, and increased MBOAT7 expression correlates with poor survival. Genetic deletion of MBOAT7 in ccRCC cells decreases proliferation and induces cell cycle arrest, and MBOAT7−/− cells fail to form tumors in vivo. RNAseq of MBOAT7−/− cells identified alterations in cell migration and extracellular matrix organization that were functionally validated in migration assays. Conclusions This study highlights the accumulation of AA-PI in ccRCC and demonstrates a novel way to decrease the AA-PI pool in ccRCC by limiting MBOAT7. Our data reveal that metastatic ccRCC is associated with altered AA-PI metabolism and identify MBOAT7 as a novel target in advanced ccRCC.
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Affiliation(s)
- Chase K A Neumann
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA; Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH, 44195, USA
| | - Daniel J Silver
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Varadharajan Venkateshwari
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Renliang Zhang
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - C Alicia Traughber
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA; Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH, 44195, USA
| | - Christopher Przybycin
- Robert J. Tomsich Pathology and Laboratory Medicine Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Defne Bayik
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Jonathan D Smith
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA; Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH, 44195, USA
| | - Justin D Lathia
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA; Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH, 44195, USA; Rose Ella Burkhardt Brain Tumor and Neuro-Oncology Center, Cleveland Clinic, Cleveland, OH, 44195, USA; Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Brian I Rini
- Department of Hematology and Oncology, Taussig Cancer Institute, Cleveland Clinic Cleveland, OH, 44195, USA; Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - J Mark Brown
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA; Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH, 44195, USA; Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, 44106, USA; Center for Microbiome and Human Health, Cleveland Clinic Foundation, Cleveland, OH, 44195, USA.
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15
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Lian G, Chen S, Ouyang M, Li F, Chen L, Yang J. Colon Cancer Cell Secretes EGF to Promote M2 Polarization of TAM Through EGFR/PI3K/AKT/mTOR Pathway. Technol Cancer Res Treat 2019; 18:1533033819849068. [PMID: 31088266 PMCID: PMC6535704 DOI: 10.1177/1533033819849068] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Background: Tumor environment has been recognized to affect cancer cell progression, such as tumor-associated macrophages. However, increasing evidences suggest that tumor cells are capable of regulating polarization of tumor-associated macrophages. In this study, we investigate the mechanism of how colon cancer cell impacts tumor-associated macrophages polarization. Methods: We employed flow cytometry to detect marker molecules on macrophage membrane, such as CD68, CD16, and CD204. In addition, we used enzyme-linked immunosorbent assay to examine the level of these cytokines (interleukin-6, interleukin-1β, interleukin-10, and Arginase-1) secreted by colon cancer cells into the culture medium. Western blot was utilized to probe downstream proteins of epidermal growth factor receptor (EGFR)/phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway. Results: We cocultured colon cancer cell lines (HCT8 or HCT116) with human myeloid leukemia mononuclear cells (THP-1) and found that interleukin-6 and interleukin-1β levels were reduced, and instead, interleukin-10 and Arginase-1 levels were elevated, suggesting that colon cancer cells contributed to M2 polarization of THP-1. Meanwhile, high level of various growth factors (transforming growth factor-β [TGF-β], epidermal growth factor [EGF], and hepatocyte growth factor [HGF]) was observed in the medium of THP-1 cocultured with colon cancer cells. Furthermore, the protein level of phosphorylated PI3K, AKT, and mTOR significantly increased in THP-1 cell cocultured with colon cancer cells compared to THP-1 group. Besides, we established that colon cancer cells exerted their stimulatory effect on M2 polarization of macrophage from monocyte THP-1 using EGFR antibody mAb225 and PI3K inhibitor LY294002. Conclusion: We provide evidence that EGF which are secreted by colon cancer cells play contributory role in M2 polarization of macrophages, which support the notion that tumor environment, including tumor-associated macrophages, can be targeted to develop effective strategies for treating cancer.
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Affiliation(s)
- Guanghui Lian
- 1 Department of Gastroenterology, Xiangya Hospital, Central South University, Changsha, People's Republic of China
| | - Shuijiao Chen
- 1 Department of Gastroenterology, Xiangya Hospital, Central South University, Changsha, People's Republic of China
| | - Miao Ouyang
- 1 Department of Gastroenterology, Xiangya Hospital, Central South University, Changsha, People's Republic of China
| | - Fujun Li
- 1 Department of Gastroenterology, Xiangya Hospital, Central South University, Changsha, People's Republic of China
| | - Linlin Chen
- 1 Department of Gastroenterology, Xiangya Hospital, Central South University, Changsha, People's Republic of China
| | - Junwen Yang
- 1 Department of Gastroenterology, Xiangya Hospital, Central South University, Changsha, People's Republic of China
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Arafeh R, Samuels Y. PIK3CA in cancer: The past 30 years. Semin Cancer Biol 2019; 59:36-49. [DOI: 10.1016/j.semcancer.2019.02.002] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 01/08/2019] [Accepted: 02/07/2019] [Indexed: 02/07/2023]
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17
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Margaria JP, Campa CC, De Santis MC, Hirsch E, Franco I. The PI3K/Akt/mTOR pathway in polycystic kidney disease: A complex interaction with polycystins and primary cilium. Cell Signal 2019; 66:109468. [PMID: 31715259 DOI: 10.1016/j.cellsig.2019.109468] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2019] [Revised: 11/08/2019] [Accepted: 11/08/2019] [Indexed: 12/19/2022]
Abstract
Over-activation of the PI3K/Akt/mTOR network is a well-known pathogenic event that leads to hyper-proliferation. Pharmacological targeting of this pathway has been developed for the treatment of multiple diseases, including cancer. In polycystic kidney disease (PKD), the mTOR cascade promotes cyst growth by boosting proliferation, size and metabolism of kidney tubule epithelial cells. Therefore, mTOR inhibition has been tested in pre-clinical and clinical studies, but only the former showed positive results. This review reports recent discoveries describing the activity and molecular mechanisms of mTOR activation in tubule epithelial cells and cyst formation and discusses the evidence of an upstream regulation of mTOR by the PI3K/Akt axis. In particular, the complex interconnections of the PI3K/Akt/mTOR network with the principal signaling routes involved in the suppression of cyst formation are dissected. These interactions include the antagonism and the reciprocal negative regulation between mTOR complex 1 and the proteins whose deletion causes Autosomal Dominant PKD, the polycystins. In addition, the emerging role of phopshoinositides, membrane components modulated by PI3K, will be presented in the context of primary cilium signaling, cell polarization and protection from cyst formation. Overall, studies demonstrate that the activity of various members of the PI3K/Akt/mTOR network goes beyond the classical transduction of mitogenic signals and can impact several aspects of kidney tubule homeostasis and morphogenesis. These properties might be useful to guide the establishment of more effective treatment protocols to be tested in clinical trials.
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Affiliation(s)
- Jean Piero Margaria
- Molecular Biotechnology Center, Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino 10126, Italy
| | - Carlo Cosimo Campa
- Department of Biosystems Science and Engineering, ETH Zurich, 4058 Basel, Switzerland
| | - Maria Chiara De Santis
- Molecular Biotechnology Center, Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino 10126, Italy
| | - Emilio Hirsch
- Molecular Biotechnology Center, Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino 10126, Italy
| | - Irene Franco
- Department of Biosciences and Nutrition, Center for Innovative Medicine, Karolinska Institutet, 14157 Huddinge, Sweden.
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Noorolyai S, Shajari N, Baghbani E, Sadreddini S, Baradaran B. The relation between PI3K/AKT signalling pathway and cancer. Gene 2019; 698:120-128. [PMID: 30849534 DOI: 10.1016/j.gene.2019.02.076] [Citation(s) in RCA: 290] [Impact Index Per Article: 58.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 02/08/2019] [Accepted: 02/17/2019] [Indexed: 12/19/2022]
Abstract
Phosphatidylinositol 3-kinases (PI3Ks) are crucial coordinators of intracellular signalling in response to the extracellular stimulators. Hyperactivation of PI3K signalling cascades is one among the most ordinary events in human cancers. Focusing on the PI3K pathway remains both a chance and a challenge for cancer therapy. The high recurrence of phosphoinositide 3-kinase (PI3K) pathway adjustments in cancer has led to a surge in the progression of PI3K inhibitors. Recent developments incorporate a re-assessment of the oncogenic mechanisms behind PI3K pathway modifications. Receptor tyrosine kinases upstream of PI3K, the p110a catalytic fractional unit of PI3K, the downstream kinase, AKT, and therefore the negative regulator, PTEN, are all often altered in cancer. In this review, we consider about the phosphoinositide 3-kinases family and mechanisms of PI3K-Akt stimulation in cancer.
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Affiliation(s)
- Saeed Noorolyai
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Neda Shajari
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Elham Baghbani
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Sanam Sadreddini
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Behzad Baradaran
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
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PI3k and Stat3: Oncogenes that are Required for Gap Junctional, Intercellular Communication. Cancers (Basel) 2019; 11:cancers11020167. [PMID: 30717267 PMCID: PMC6406562 DOI: 10.3390/cancers11020167] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 01/21/2019] [Accepted: 01/26/2019] [Indexed: 12/12/2022] Open
Abstract
Gap junctional, intercellular communication (GJIC) is interrupted in cells transformed by oncogenes such as activated Src. The Src effector, Ras, is required for this effect, so that Ras inhibition restores GJIC in Src-transformed cells. Interestingly, the inhibition of the Src effector phosphatidyl-inositol-3 kinase (PI3k) or Signal Transducer and Activator of Transcription-3 (Stat3) pathways does not restore GJIC. In the contrary, inhibition of PI3k or Stat3 in non-transformed rodent fibroblasts or epithelial cells or certain human lung carcinoma lines with extensive GJIC inhibits communication, while mutational activation of PI3k or Stat3 increases GJIC. Therefore, it appears that oncogenes such as activated Src have a dual role upon GJIC; acting as inhibitors of communication through the Ras pathway, and as activators through activation of PI3k or Stat3. In the presence of high Src activity the inhibitory functions prevail so that the net effect is gap junction closure. PI3k and Stat3 constitute potent survival signals, so that their inhibition in non-transformed cells triggers apoptosis which, in turn, has been independently demonstrated to suppress GJIC. The interruption of gap junctional communication would confine the apoptotic event to single cells and this might be essential for the maintenance of tissue integrity. We hypothesize that the GJIC activation by PI3k or Stat3 may be linked to their survival function.
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Phosphoproteomic analysis reveals PAK2 as a therapeutic target for lapatinib resistance in HER2-positive breast cancer cells. Biochem Biophys Res Commun 2018; 505:187-193. [PMID: 30243723 DOI: 10.1016/j.bbrc.2018.09.086] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 09/02/2018] [Accepted: 09/13/2018] [Indexed: 11/24/2022]
Abstract
The human epidermal growth factor receptor 2 (HER2)-positive breast cancer with overexpression of HER2 accounts for approximately 25% of breast cancers and is more aggressive than other types of breast cancer. Lapatinib has been widely used as a HER2-targeted therapy, however, a number of patients develop lapatinib resistance and still suffer from poor prognosis. Therefore, it is essential to identify novel therapeutic targets that could overcome lapatinib resistance. In this study, we carried out phosphoproteomic analysis of lapatinib sensitive and resistant cell lines (SKBR3 and SKBR3-LR) using stable isotope labeling with amino acids in cell culture (SILAC). We identified 3808 phosphopeptides from 1807 proteins and then analyzed signaling pathways, Gene Ontology, and protein-protein interaction networks. Finally, we identified PAK2 as a therapeutic target from the network analysis and validated that PAK2 knockdown and PAK inhibitor treatment resensitize the lapatinib resistant cells to lapatinib. This results suggest that PAK2 is a potent therapeutic target to overcome acquired lapatinib resistance in HER2-positive breast cancer cells.
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Kong JR, Wei W, Liang QJ, Qiao XL, Kang H, Liu Y, Wang WN. Identifying the function of LvPI3K during the pathogenic infection of Litopenaeus vannamei by Vibrio alginolyticus. FISH & SHELLFISH IMMUNOLOGY 2018; 76:355-367. [PMID: 29544772 DOI: 10.1016/j.fsi.2018.03.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 03/05/2018] [Accepted: 03/10/2018] [Indexed: 06/08/2023]
Abstract
It is well known that PI3K regulates various processes in mammalian cells by generating a secondary messenger that later activates AKT. However, its innate immune function in crustaceans remains unclear. We report the characterization of Litopenaeus vannamei PI3K (LvPI3K) for investigating how PI3K participates in the innate immunity of crustaceans. Full-length LvPI3K cDNA was 3357 bp long, with a 3222 bp open reading frame (ORF) that encodes a putative protein of 1292 amino acids. The PI3K catalytic domain (PI3Kc) of LvPI3K was found to be rather conserved when the PI3Ks from other species were analyzed. The LvPI3K protein was shown to be localized to the cytoplasm of Drosophila S2 cells, while LvPI3K mRNA was ubiquitously expressed in healthy L. vannamei, with the highest expression found in hemolymph. A dual luciferase reporter gene assay demonstrated that LvPI3K overexpression activated the promoter of antibacterial peptide LvPEN4 in a dose-dependent manner. However, the addition of PDTC, a specific inhibitor of NF-κB, suppressed the LvPI3K-induced LvPEN4 promoter activation. Moreover, Vibrio alginolyticus challenge induced a rapid up-regulation of LvPI3K expression. Further experiments showed that LvPI3K silencing in shrimp challenged with V. alginolyticus significantly increased Vibrio number, ROS production and DNA damage in the hemolymph, as well as significantly decreased total hemocyte count. The mRNA levels of certain molecules related to LvPI3K signaling, such as LvAKT and LvPEN4, also decreased following LvPI3K silencing. Taken together, these results suggest that LvPI3K regulates the downstream signal component LvPEN4 and functions in V. alginolyticus resistance.
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Affiliation(s)
- Jing-Rong Kong
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, College of Life Science, South China Normal University, Guangzhou 510631, PR China
| | - Wei Wei
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, College of Life Science, South China Normal University, Guangzhou 510631, PR China
| | - Qing-Jian Liang
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, College of Life Science, South China Normal University, Guangzhou 510631, PR China
| | - Xue-Li Qiao
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, College of Life Science, South China Normal University, Guangzhou 510631, PR China
| | - Huan Kang
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, College of Life Science, South China Normal University, Guangzhou 510631, PR China
| | - Yuan Liu
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, College of Life Science, South China Normal University, Guangzhou 510631, PR China.
| | - Wei-Na Wang
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, College of Life Science, South China Normal University, Guangzhou 510631, PR China.
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Powis G. Recent Advances in the Development of Anticancer Drugs that Act against Signalling Pathways. TUMORI JOURNAL 2018; 80:69-87. [PMID: 8016910 DOI: 10.1177/030089169408000201] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Cancer can be considered a disease of deranged intracellular signalling. The intracellular signalling pathways that mediate the effects of oncogenes on cell growth and transformation present attractive targets for the development of new classes of drugs for the prevention and treatment of cancer. This is a new approach to developing anticancer drugs and the potential, as well as some of the problems, inherent in the approach are discussed. Anticancer drugs that produce their effects by disrupting signalling pathways are already in clinical trial. Some properties of these drugs, as well as other inhibitors of signalling pathways under development as potential anticancer drugs, are reviewed.
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Affiliation(s)
- G Powis
- Arizona Cancer Center, University of Arizona Health Sciences Center, Tucson 85724
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Activation of oncogenic tyrosine kinase signaling promotes insulin receptor-mediated cone photoreceptor survival. Oncotarget 2018; 7:46924-46942. [PMID: 27391439 PMCID: PMC5216914 DOI: 10.18632/oncotarget.10447] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 06/26/2016] [Indexed: 01/18/2023] Open
Abstract
In humans, daylight vision is primarily mediated by cone photoreceptors. These cells die in age-related retinal degenerations. Prolonging the life of cones for even one decade would have an enormous beneficial effect on usable vision in an aging population. Photoreceptors are postmitotic, but shed 10% of their outer segments daily, and must synthesize the membrane and protein equivalent of a proliferating cell each day. Although activation of oncogenic tyrosine kinase and inhibition of tyrosine phosphatase signaling is known to be essential for tumor progression, the cellular regulation of this signaling in postmitotic photoreceptor cells has not been studied. In the present study, we report that a novel G-protein coupled receptor–mediated insulin receptor (IR) signaling pathway is regulated by non-receptor tyrosine kinase Src through the inhibition of protein tyrosine phosphatase IB (PTP1B). We demonstrated the functional significance of this pathway through conditional deletion of IR and PTP1B in cones, in addition to delaying the death of cones in a mouse model of cone degeneration by activating the Src. This is the first study demonstrating the molecular mechanism of a novel signaling pathway in photoreceptor cells, which provides a window of opportunity to save the dying cones in retinal degenerative diseases.
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Vasireddi M, Hilliard JK. Regulation of PI3K/Akt dependent apoptotic markers during b virus infection of human and macaque fibroblasts. PLoS One 2017; 12:e0178314. [PMID: 28558072 PMCID: PMC5448769 DOI: 10.1371/journal.pone.0178314] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 05/11/2017] [Indexed: 12/17/2022] Open
Abstract
B virus (Macacine herpesvirus 1), a simplex virus endemic in macaques, causes encephalitis, encephalomyelitis, and death in 80% of untreated zoonotically infected humans with delayed or no treatment. Here we report a significant difference in PI3K/Akt-dependent apoptosis between B virus infected human and macaque dermal fibroblasts. Our data show that B virus infection in either human or macaque fibroblasts results in activation of Akt via PI3K and this activation does not require viral de novo protein synthesis. Inhibition of PI3K with LY294002 results in a significant reduction of viral titers in B virus infected macaque and human fibroblasts with only a modest difference in the reduction of virus titers between the two cell types. We, therefore, tested the hypothesis that B virus results in the phosphorylation of Akt (S473), which prevents apoptosis, enhancing virus replication in B virus infected macaque dermal fibroblasts. We observed markers of intrinsic apoptosis when PI3K activation of Akt was inhibited in B virus infected macaque cells, while, these apoptotic markers were absent in B virus infected human fibroblasts under the same conditions. From these data we suggest that PI3K activates Akt in B virus infected macaque and human fibroblasts, but this enhances virus replication in macaque fibroblast cells by blocking apoptosis.
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Affiliation(s)
- Mugdha Vasireddi
- Viral Immunology Center, Biology Department, Georgia State University, Atlanta, GA, United States of America
| | - Julia K. Hilliard
- Viral Immunology Center, Biology Department, Georgia State University, Atlanta, GA, United States of America
- * E-mail:
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A Transformation-Defective Polyomavirus Middle T Antigen with a Novel Defect in PI3 Kinase Signaling. J Virol 2017; 91:JVI.01774-16. [PMID: 27852846 DOI: 10.1128/jvi.01774-16] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 10/29/2016] [Indexed: 02/06/2023] Open
Abstract
Middle T antigen (MT), the principal oncoprotein of murine polyomavirus, transforms by association with cellular proteins. Protein phosphatase 2A (PP2A), YAP, Src family tyrosine kinases, Shc, phosphatidylinositol 3-kinase (PI3K), and phospholipase C-γ1 (PLCγ1) have all been implicated in MT transformation. Mutant dl1015, with deletion of residues 338 to 347 in the C-terminal region, has been an enigma, because the basis for its transformation defect has not been apparent. This work probes the dl1015 region of MT. Because the region is proline rich, the hypothesis that it targets Src homology domain 3 (SH3) domains was tested, but mutation of the putative SH3 binding motif did not affect transformation. During this work, two point mutants, W348R and E349K, were identified as transformation defective. Extensive analysis of the E349K mutant is described here. Similar to wild-type MT, the E349K mutant associates with PP2A, YAP, tyrosine kinases, Shc, PI3 kinase, and PLCγ1. The E349K mutant was examined to determine the mechanism for its transformation defect. Assays of cell localization and membrane targeting showed no obvious difference in localization. Src association was normal as assayed by in vitro kinase and MT phosphopeptide mapping. Shc activation was confirmed by its tyrosine phosphorylation. Association of type 1 PI3K with MT was demonstrated by coimmunoprecipitation, showing both PI3K subunits and in vitro activity. Nonetheless, expression of the mutants failed to lead to the activation of two known downstream targets of PI3K, Akt and Rac-1. Strikingly, despite normal association of the E349K mutant with PI3K, cells expressing the mutant failed to elevate phosphatidylinositol (3,4,5)-trisphosphate (PIP3) in mutant-expressing cells. These results indicate a novel unsuspected aspect to PI3K control. IMPORTANCE The gene coding for middle T antigen (MT) is the murine polyomavirus oncogene most responsible for tumor formation. Its study has a history of uncovering novel aspects of mammalian cell regulation. The importance of PI3K activity and tyrosine phosphorylation are two examples of insights coming from MT. This study describes new mutants unable to transform like the wild type that point to novel regulation of PI3K signaling. Previous mutants were defective in PI3K because they failed to bind the enzyme and bring the activity to the membrane. These mutants recruit PI3K activity like the wild type, but fail to elevate the cellular level of PIP3, the product used to signal downstream of PI3K. As a result, they fail to activate either Akt or Rac1, explaining the transformation defect.
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Lupieri A, Smirnova N, Malet N, Gayral S, Laffargue M. PI3K signaling in arterial diseases: Non redundant functions of the PI3K isoforms. Adv Biol Regul 2015; 59:4-18. [PMID: 26238239 DOI: 10.1016/j.jbior.2015.06.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 06/15/2015] [Accepted: 06/15/2015] [Indexed: 06/04/2023]
Abstract
Cardiovascular diseases are the most common cause of death around the world. This includes atherosclerosis and the adverse effects of its treatment, such as restenosis and thrombotic complications. The development of these arterial pathologies requires a series of highly-intertwined interactions between immune and arterial cells, leading to specific inflammatory and fibroproliferative cellular responses. In the last few years, the study of phosphoinositide 3-kinase (PI3K) functions has become an attractive area of investigation in the field of arterial diseases, especially since inhibitors of specific PI3K isoforms have been developed. The PI3K family includes 8 members divided into classes I, II or III depending on their substrate specificity. Although some of the different isoforms are responsible for the production of the same 3-phosphoinositides, they each have specific, non-redundant functions as a result of differences in expression levels in different cell types, activation mechanisms and specific subcellular locations. This review will focus on the functions of the different PI3K isoforms that are suspected as having protective or deleterious effects in both the various immune cells and types of cell found in the arterial wall. It will also discuss our current understanding in the context of which PI3K isoform(s) should be targeted for future therapeutic interventions to prevent or treat arterial diseases.
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Affiliation(s)
- Adrien Lupieri
- INSERM, U1048, I2MC and Université Toulouse III, Toulouse, F-31300, France
| | - Natalia Smirnova
- INSERM, U1048, I2MC and Université Toulouse III, Toulouse, F-31300, France
| | - Nicole Malet
- INSERM, U1048, I2MC and Université Toulouse III, Toulouse, F-31300, France
| | - Stéphanie Gayral
- INSERM, U1048, I2MC and Université Toulouse III, Toulouse, F-31300, France
| | - Muriel Laffargue
- INSERM, U1048, I2MC and Université Toulouse III, Toulouse, F-31300, France.
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Geletu M, Guy S, Greer S, Raptis L. Differential effects of polyoma virus middle tumor antigen mutants upon gap junctional, intercellular communication. Exp Cell Res 2015; 336:223-31. [PMID: 26187405 DOI: 10.1016/j.yexcr.2015.07.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 07/07/2015] [Accepted: 07/13/2015] [Indexed: 12/18/2022]
Abstract
Gap junctions are channels that connect the cytoplasm of adjacent cells. Oncogenes such as the middle Tumor antigen of polyoma virus (mT) are known to suppress gap junctional, intercellular communication (GJIC). mT associates with and is tyrosine-phosphorylated by cSrc family members. Specific mT phosphotyrosines provide docking sites for the phosphotyrosine binding domain of Shc (mT-tyr250) or the SH2 domain of the regulatory subunit of the phosphatidylinositol-3 kinase (PI3k, mT-tyr315). Binding results in the activation of their downstream signaling cascades, Ras/Raf/Erk and PI3 kinase/Akt, respectively, both of which are needed for full neoplastic transformation. To examine the effect of mT-initiated pathways upon gap junctional communication, GJIC was quantitated in rat liver epithelial T51B cells expressing mT-mutants, using a novel technique of in situ electroporation. The results demonstrate for the first time that, although even low levels of wild-type mT are sufficient to interrupt gap junctional communication, GJIC suppression still requires an intact tyr-250 site, that is activation of the Ras pathway. In sharp contrast, activation of the PI3k pathway is not required for GJIC suppression, indicating that GJIC suppression is independent of full neoplastic conversion and the concomitant morphological changes. Interestingly, expression of a constitutively active, myristylated form of the catalytic subunit of PI3k, p110, or the constitutively active mutants E545K and H1047R increased GJIC, while pharmacological inhibition of PI3k eliminated communication. Therefore, although PI3k is growth promoting and in an activated form it can act as an oncogene, it actually plays a positive role upon gap junctional, intercellular communication.
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Affiliation(s)
- Mulu Geletu
- Department of Biomedical and Molecular Sciences and Department of Pathology and Molecular Medicine, Queen's University, Kingston, Ontario, Canada K7L 3N6
| | - Stephanie Guy
- Department of Biomedical and Molecular Sciences and Department of Pathology and Molecular Medicine, Queen's University, Kingston, Ontario, Canada K7L 3N6
| | - Samantha Greer
- Department of Biomedical and Molecular Sciences and Department of Pathology and Molecular Medicine, Queen's University, Kingston, Ontario, Canada K7L 3N6
| | - Leda Raptis
- Department of Biomedical and Molecular Sciences and Department of Pathology and Molecular Medicine, Queen's University, Kingston, Ontario, Canada K7L 3N6.
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Gupta VK, Rajala A, Rajala RVS. Non-canonical regulation of phosphatidylinositol 3-kinase gamma isoform activity in retinal rod photoreceptor cells. Cell Commun Signal 2015; 13:7. [PMID: 25644171 PMCID: PMC4326362 DOI: 10.1186/s12964-015-0087-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2014] [Accepted: 01/20/2015] [Indexed: 12/31/2022] Open
Abstract
Background Phosphatidylinositol 3-Kinases (PI3Ks) are a family of lipid kinases that phosphorylate the D3-hydroxyls of the inositol ring of phosphoinositides, and are responsible for coordinating a diverse range of cellular functions. A canonical pathway of activation of PI3Ks through the interaction of RA-domain with Ras proteins has been well established. In retinal photoreceptors, we have identified a non-canonical pathway of PI3Kγ activation through the interaction of its RA-domain with a putative Ras-like domain (RLD) in alpha subunit of cyclic nucleotide-gated channel (CNGA1) in retinal rod photoreceptors. Results The interaction between PI3Kγ and CNGA1 does not appear to play a role in regulation of CNG channel activity, but PI3Kγ uses CNGA1 as an anchoring module to achieve close proximity to its substrate to generate D3-phosphoinositides. Conclusions Our studies suggest a functional non-canonical PI3Kγ activation in retinal rod photoreceptor cells.
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Abstract
The importance of PTEN in cellular function is underscored by the frequency of its deregulation in cancer. PTEN tumor-suppressor activity depends largely on its lipid phosphatase activity, which opposes PI3K/AKT activation. As such, PTEN regulates many cellular processes, including proliferation, survival, energy metabolism, cellular architecture, and motility. More than a decade of research has expanded our knowledge about how PTEN is controlled at the transcriptional level as well as by numerous posttranscriptional modifications that regulate its enzymatic activity, protein stability, and cellular location. Although the role of PTEN in cancers has long been appreciated, it is also emerging as an important factor in other diseases, such as diabetes and autism spectrum disorders. Our understanding of PTEN function and regulation will hopefully translate into improved prognosis and treatment for patients suffering from these ailments.
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Affiliation(s)
- Carolyn A Worby
- Department of Pharmacology, University of California, San Diego, La Jolla, California 92093-0721;
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Martini M, De Santis MC, Braccini L, Gulluni F, Hirsch E. PI3K/AKT signaling pathway and cancer: an updated review. Ann Med 2014; 46:372-83. [PMID: 24897931 DOI: 10.3109/07853890.2014.912836] [Citation(s) in RCA: 798] [Impact Index Per Article: 79.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Despite development of novel agents targeting oncogenic pathways, matching targeted therapies to the genetic status of individual tumors is proving to be a daunting task for clinicians. To improve the clinical efficacy and to reduce the toxic side effects of treatments, a deep characterization of genetic alterations in different tumors is required. The mutational profile often evidences a gain of function or hyperactivity of phosphoinositide 3-kinases (PI3Ks) in tumors. These enzymes are activated downstream tyrosine kinase receptors (RTKs) and/or G proteins coupled receptors (GPCRs) and, via AKT, are able to induce mammalian target of rapamycin (mTOR) stimulation. Here, we elucidate the impact of class I (p110α, β, γ, and δ) catalytic subunit mutations on AKT-mediated cellular processes that control crucial mechanisms in tumor development. Moreover, the interrelation of PI3K signaling with mTOR, ERK, and RAS pathways will be discussed, exploiting the potential benefits of PI3K signaling inhibitors in clinical use.
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Affiliation(s)
- Miriam Martini
- Molecular Biotechnology Center, Department of Molecular Biotechnology and Health Sciences, University of Turin , Italy
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31
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Abstract
The phosphoinositide 3-kinase (PI 3-K) signal relay pathway represents arguably one of the most intensely studied mechanisms by which extracellular signals elicit cellular responses through the generation of second messengers that are associated with cell growth and transformation. This chapter reviews the many landmark discoveries in the PI 3-K signaling pathway in biology and disease, from the identification of a novel phosphoinositide kinase activity associated with transforming oncogenes in the 1980s, to the identification of oncogenic mutations in the catalytic subunit of PI 3-K in the mid 2000s. Two and a half decades of intense research have provided clear evidence that the PI 3-K pathway controls virtually all aspects of normal cellular physiology, and that deregulation of one or more proteins that regulate or transduce the PI 3-K signal ultimately leads to human pathology. The most recent efforts have focused on the development of specific PI 3-K inhibitors that are currently being evaluated in clinical trials for a range of disease states.This chapter is devoted to a historical review of the landmark findings in the PI 3-K from its relatively humble beginnings in the early to mid 1980s up until the present day. When considering the key findings in the history of PI 3-K, it is essential to recognize the landmark studies by Lowell and Mabel Hokin in the 1950s who were the first to describe that extracellular agonists such as acetylcholine could stimulate the incorporation of radiolabeled phosphate into phospholipids (Hokin and Hokin 1953). Their work initiated an entirely new field of lipid signaling, and subsequent studies in the 1970s by Michell and Lapetina who linked phosphoinositide turnover to membrane-associated receptors that initiate intracellular calcium mobilization (Lapetina and Michell 1973). Later studies revealed that the phospholipase-mediated breakdown of the same minor membrane phospholipids such as PtdIns-4,5-P(2) (phosphatidylinositol-4,5-bisphosphate) is responsible for the release of two additional key second messengers, diacylglycerol (DG) and IP(3) (inositol-1,4,5-trisphosphate) (Kirk et al. 1981; Berridge 1983; Berridge et al. 1983). Berridge, Irvine and Schulz then revealed that one of the byproducts of this lipid signal relay pathway is the release of calcium from intracellular stores such as the endoplasmic reticulum (Streb et al. 1983). Finally, pioneering studies by Nishizuka in the late 1970s identified PKC (protein kinase C) as a phospholipid and diacylglycerol-activated serine/threonine protein kinase (Inoue et al. 1977; Takai et al. 1977). At this point, it probably seemed to most at the time that the story was complete, such that hydrolysis of phosphoinositides such as PtdIns-4,5-P(2) and PtdIns-4-P would account for the major mechanisms of agonist-stimulated lipid signaling leading to physiological responses. On the contrary, the story was far from complete and was about to become a lot more complex.
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Affiliation(s)
- Alex Toker
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, EC/CLS-633A, 02130, Boston, MA, USA,
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Xie S, Chen M, Yan B, He X, Chen X, Li D. Identification of a role for the PI3K/AKT/mTOR signaling pathway in innate immune cells. PLoS One 2014; 9:e94496. [PMID: 24718556 PMCID: PMC3981814 DOI: 10.1371/journal.pone.0094496] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 03/16/2014] [Indexed: 01/08/2023] Open
Abstract
The innate immune system is the first line of host defense against infection and involves several different cell types. Here we investigated the role of the phosphatidylinositol 3 kinase (PI3K) signaling pathway in innate immune cells. By blocking this pathway with pharmacological inhibitors, we found that the production of proinflammatory cytokines was drastically suppressed in monocytes and macrophages. Further study revealed that the suppression was mainly related to the mammalian target of rapamycin (mTOR)/p70S6K signaling. In addition, we found that the PI3K pathway was involved in macrophage motility and neovascularization. Our data provide a rationale that inhibition of the PI3K signaling pathway could be an attractive approach for the management of inflammatory disorders.
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Affiliation(s)
- Songbo Xie
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, China
| | - Miao Chen
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, China
| | - Bing Yan
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, China
| | - Xianfei He
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, China
| | - Xiwen Chen
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, China
- * E-mail: (DL); (XC)
| | - Dengwen Li
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, China
- * E-mail: (DL); (XC)
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PI3K. Mol Oncol 2013. [DOI: 10.1017/cbo9781139046947.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Spangle JM, Munger K. The HPV16 E6 oncoprotein causes prolonged receptor protein tyrosine kinase signaling and enhances internalization of phosphorylated receptor species. PLoS Pathog 2013; 9:e1003237. [PMID: 23516367 PMCID: PMC3597533 DOI: 10.1371/journal.ppat.1003237] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 01/28/2013] [Indexed: 01/13/2023] Open
Abstract
The high-risk human papillomavirus (HPV) E6 proteins are consistently expressed in HPV-associated lesions and cancers. HPV16 E6 sustains the activity of the mTORC1 and mTORC2 signaling cascades under conditions of growth factor deprivation. Here we report that HPV16 E6 activated mTORC1 by enhanced signaling through receptor protein tyrosine kinases, including epidermal growth factor receptor and insulin receptor and insulin-like growth factor receptors. This is evidenced by sustained signaling through these receptors for several hours after growth factor withdrawal. HPV16 E6 increased the internalization of activated receptor species, and the signaling adaptor protein GRB2 was shown to be critical for HPV16 E6 mediated enhanced EGFR internalization and mTORC1 activation. As a consequence of receptor protein kinase mediated mTORC1 activation, HPV16 E6 expression increased cellular migration of primary human epithelial cells. This study identifies a previously unappreciated mechanism by which HPV E6 proteins perturb host-signaling pathways presumably to sustain protein synthesis during the viral life cycle that may also contribute to cellular transforming activities of high-risk HPV E6 proteins. High-risk human papillomavirus infections are associated with nearly all cases of cervical cancer. HPVs infect basal epithelial cells but virion production is restricted to the outer, terminally differentiated layers of the infected epithelia where supply of nutrients and growth factors may be limited. High-risk HPV E6 proteins have been shown to activate mTORC1 signaling and increase cap dependent translation. Here we show that HPV16 E6 activates the mTORC1 and MAP kinase signaling pathways through activating receptor protein tyrosine kinases (RPTKs) and increases EGFR internalization, even after growth factor withdrawal. The signaling adaptor protein GRB2 is a critical mediator of HPV16 E6 mediated EGFR internalization and mTORC1 activation. Lastly, we demonstrate that HPV16 E6 mediated activation of RPTK and mTORC1 signaling causes increased cellular migration even after growth factor withdrawal. These results suggest a previously unappreciated mechanism by which HPV E6 proteins may support the viral life cycle and that may contribute to the transforming activities of high-risk HPV E6 proteins. Hence, inhibition of RPTK signaling networks may be evaluated as a therapeutic strategy for HPV-associated lesions and cancers.
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Affiliation(s)
- Jennifer M. Spangle
- Division of Infectious Diseases, Brigham and Women's Hospital, Department of Medicine and Committee on Virology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Karl Munger
- Division of Infectious Diseases, Brigham and Women's Hospital, Department of Medicine and Committee on Virology, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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Abstract
Retroviruses are the original source of oncogenes. The discovery and characterization of these genes was made possible by the introduction of quantitative cell biological and molecular techniques for the study of tumour viruses. Key features of all retroviral oncogenes were first identified in src, the oncogene of Rous sarcoma virus. These include non-involvement in viral replication, coding for a single protein and cellular origin. The MYC, RAS and ERBB oncogenes quickly followed SRC, and these together with PI3K are now recognized as crucial driving forces in human cancer.
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Affiliation(s)
- Peter K Vogt
- The Scripps Research Institute, La Jolla, California 92037, USA.
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36
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Lee H, Jung KH, Jeong Y, Hong S, Hong SS. HS-173, a novel phosphatidylinositol 3-kinase (PI3K) inhibitor, has anti-tumor activity through promoting apoptosis and inhibiting angiogenesis. Cancer Lett 2012; 328:152-9. [PMID: 22929971 DOI: 10.1016/j.canlet.2012.08.020] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Revised: 08/16/2012] [Accepted: 08/16/2012] [Indexed: 12/19/2022]
Abstract
We synthesized a novel imidazopyridine analogue, a PI3Kα inhibitor HS-173 and investigated anti-cancer capacity in human cancer cells. HS-173 inhibited the PI3K signaling pathway, and showed anti-proliferative effects on cancer cells. Also, HS-173 induced cell cycle arrest at the G(2)/M phase and apoptosis. In addition, HS-173 decreased the expression HIF-1α and VEGF which play an important role in angiogenesis. This effect was confirmed by the suppression of tube formation and migration assay in vitro. Furthermore, HS-173 diminished blood vessel formation in the Matrigel plug assay in mice. Therefore, HS-173 is considered as a novel drug candidate to treat cancer patients.
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Affiliation(s)
- Hyunseung Lee
- Department of Biomedical Sciences, College of Medicine, Inha University, 3-ga, Sinheung-dong, Jung-gu, Incheon 400-712, Republic of Korea
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37
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Abstract
Over the past two decades, our understanding of phospoinositide 3-kinases (PI3Ks) has progressed from the identification of an enzymatic activity associated with growth factors, GPCRs and certain oncogene products to a disease target in cancer and inflammation, with PI3K inhibitors currently in clinical trials. Elucidation of PI3K-dependent networks led to the discovery of the phosphoinositide-binding PH, PX and FYVE domains as conduits of intracellular lipid signalling, the determination of the molecular function of the tumour suppressor PTEN and the identification of AKT and mTOR protein kinases as key regulators of cell growth. Here we look back at the main discoveries that shaped the PI3K field.
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38
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Chang Y, Moore PS. Merkel cell carcinoma: a virus-induced human cancer. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2011; 7:123-44. [PMID: 21942528 DOI: 10.1146/annurev-pathol-011110-130227] [Citation(s) in RCA: 150] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Merkel cell polyomavirus (MCV) is the first polyomavirus directly linked to human cancer, and its recent discovery helps to explain many of the enigmatic features of Merkel cell carcinoma (MCC). MCV is clonally integrated into MCC tumor cells, which then require continued MCV oncoprotein expression to survive. The integrated viral genomes have a tumor-specific pattern of tumor antigen gene mutation that incapacitates viral DNA replication. This human cancer virus provides a new model in which a common, mostly harmless member of the human viral flora can initiate cancer if it acquires a precise set of mutations in a host with specific susceptibility factors, such as age and immune suppression. Identification of this tumor virus has led to new opportunities for early diagnosis and targeted treatment of MCC.
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Affiliation(s)
- Yuan Chang
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA.
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39
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Shuda M, Kwun HJ, Feng H, Chang Y, Moore PS. Human Merkel cell polyomavirus small T antigen is an oncoprotein targeting the 4E-BP1 translation regulator. J Clin Invest 2011; 121:3623-34. [PMID: 21841310 DOI: 10.1172/jci46323] [Citation(s) in RCA: 276] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Accepted: 06/29/2011] [Indexed: 12/11/2022] Open
Abstract
Merkel cell polyomavirus (MCV) is the recently discovered cause of most Merkel cell carcinomas (MCCs), an aggressive form of nonmelanoma skin cancer. Although MCV is known to integrate into the tumor cell genome and to undergo mutation, the molecular mechanisms used by this virus to cause cancer are unknown. Here, we show that MCV small T (sT) antigen is expressed in most MCC tumors, where it is required for tumor cell growth. Unlike the closely related SV40 sT, MCV sT transformed rodent fibroblasts to anchorage- and contact-independent growth and promoted serum-free proliferation of human cells. These effects did not involve protein phosphatase 2A (PP2A) inhibition. MCV sT was found to act downstream in the mammalian target of rapamycin (mTOR) signaling pathway to preserve eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1) hyperphosphorylation, resulting in dysregulated cap-dependent translation. MCV sT-associated 4E-BP1 serine 65 hyperphosphorylation was resistant to mTOR complex (mTORC1) and mTORC2 inhibitors. Steady-state phosphorylation of other downstream Akt-mTOR targets, including S6K and 4E-BP2, was also increased by MCV sT. Expression of a constitutively active 4E-BP1 that could not be phosphorylated antagonized the cell transformation activity of MCV sT. Taken together, these experiments showed that 4E-BP1 inhibition is required for MCV transformation. Thus, MCV sT is an oncoprotein, and its effects on dysregulated cap-dependent translation have clinical implications for the prevention, diagnosis, and treatment of MCV-related cancers.
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Affiliation(s)
- Masahiro Shuda
- Cancer Virology Program, University of Pittsburgh Cancer Institute, 5117 Centre Avenue, Pittsburgh, Pennsylvania 15213, USA
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40
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Ou HD, May AP, O'Shea CC. The critical protein interactions and structures that elicit growth deregulation in cancer and viral replication. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2011; 3:48-73. [PMID: 21061422 DOI: 10.1002/wsbm.88] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
One of the greatest challenges in biomedicine is to define the critical targets and network interactions that are subverted to elicit growth deregulation in human cells. Understanding and developing rational treatments for cancer requires a definition of the key molecular targets and how they interact to elicit the complex growth deregulation phenotype. Viral proteins provide discerning and powerful probes to understand both how cells work and how they can be manipulated using a minimal number of components. The small DNA viruses have evolved to target inherent weaknesses in cellular protein interaction networks to hijack the cellular DNA and protein replication machinery. In the battle to escape the inevitability of senescence and programmed cell death, cancers have converged on similar mechanisms, through the acquisition and selection of somatic mutations that drive unchecked cellular replication in tumors. Understanding the dynamic mechanisms through which a minimal number of viral proteins promote host cells to undergo unscheduled and pathological replication is a powerful strategy to identify critical targets that are also disrupted in cancer. Viruses can therefore be used as tools to probe the system-wide protein-protein interactions and structures that drive growth deregulation in human cells. Ultimately this can provide a path for developing system context-dependent therapeutics. This review will describe ongoing experimental approaches using viruses to study pathways deregulated in cancer, with a particular focus on viral cellular protein-protein interactions and structures.
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Affiliation(s)
- Horng D Ou
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
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41
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Courtney KD, Corcoran RB, Engelman JA. The PI3K pathway as drug target in human cancer. J Clin Oncol 2010; 28:1075-83. [PMID: 20085938 PMCID: PMC2834432 DOI: 10.1200/jco.2009.25.3641] [Citation(s) in RCA: 961] [Impact Index Per Article: 68.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Accepted: 11/18/2009] [Indexed: 12/13/2022] Open
Abstract
The phosphatidylinositol 3-kinase (PI3K) signaling axis impacts on cancer cell growth, survival, motility, and metabolism. This pathway is activated by several different mechanisms in cancers, including somatic mutation and amplification of genes encoding key components. In addition, PI3K signaling may serve integral functions for noncancerous cells in the tumor microenvironment. Consequently, therapeutics targeting the PI3K pathway are being developed at a rapid pace, and preclinical and early clinical studies are beginning to suggest specific strategies to effectively use them. However, the central role of PI3K signaling in a large array of diverse biologic processes raises concerns about its use in therapeutics and increases the need to develop sophisticated strategies for its use. In this review, we will discuss how PI3K signaling affects the growth and survival of tumor cells. From this vantage, we will consider how inhibitors of the PI3K signaling cascade, either alone or in combination with other therapeutics, can most effectively be used for the treatment of cancer.
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Affiliation(s)
- Kevin D. Courtney
- From the Department of Medicine, Harvard Medical School; Department of Medical Oncology, Dana-Farber Cancer Institute; Beth Israel Deaconess Medical Center Cancer Center; Massachusetts General Hospital Cancer Center, Boston, MA
| | - Ryan B. Corcoran
- From the Department of Medicine, Harvard Medical School; Department of Medical Oncology, Dana-Farber Cancer Institute; Beth Israel Deaconess Medical Center Cancer Center; Massachusetts General Hospital Cancer Center, Boston, MA
| | - Jeffrey A. Engelman
- From the Department of Medicine, Harvard Medical School; Department of Medical Oncology, Dana-Farber Cancer Institute; Beth Israel Deaconess Medical Center Cancer Center; Massachusetts General Hospital Cancer Center, Boston, MA
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42
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Vanhaesebroeck B, Vogt PK, Rommel C. PI3K: from the bench to the clinic and back. Curr Top Microbiol Immunol 2010; 347:1-19. [PMID: 20549473 DOI: 10.1007/82_2010_65] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
From humble beginnings over 25 years ago as a lipid kinase activity associated with certain oncoproteins, PI3K (phosphoinositide 3-kinase) has been catapulted to the forefront of drug development in cancer, immunity and thrombosis, with the first clinical trials of PI3K pathway inhibitors now in progress. Here, we give a brief overview of some key discoveries in the PI3K area and their impact, and include thoughts on the current state of the field, and where it could go from here.PI3K has become a very intense area of research, with over 2,000 publications on PI3K in PubMed for 2009 alone. The expectations for a therapeutic impact of intervention with PI3K activity are high, and progress in the clinical arena is being monitored by many. However, targeted therapies almost invariably encounter roadblocks, often exposing unresolved questions in the basic understanding of the target. PI3K will most likely be no exception. Below, we describe some of these early "surprises" and how these inform and shape basic science investigations.
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43
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Abstract
The PI3-K family is one of the most intensely pursued classes of drug targets. This chapter reviews some of the chemical and structural features that determine the selectivity of PI3-K inhibitors, by focusing on a few key compounds that have been instrumental in guiding our understanding of how to design drugs against this family.
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44
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Fluck MM, Schaffhausen BS. Lessons in signaling and tumorigenesis from polyomavirus middle T antigen. Microbiol Mol Biol Rev 2009; 73:542-63, Table of Contents. [PMID: 19721090 PMCID: PMC2738132 DOI: 10.1128/mmbr.00009-09] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The small DNA tumor viruses have provided a very long-lived source of insights into many aspects of the life cycle of eukaryotic cells. In recent years, the emphasis has been on cancer-related signaling. Here we review murine polyomavirus middle T antigen, its mechanisms, and its downstream pathways of transformation. We concentrate on the MMTV-PyMT transgenic mouse, one of the most studied models of breast cancer, which permits the examination of in situ tumor progression from hyperplasia to metastasis.
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Affiliation(s)
- Michele M Fluck
- Department of Microbiology and Molecular Genetics, Interdepartmental Program in Cell and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA.
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45
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Anas A, Okuda T, Kawashima N, Nakayama K, Itoh T, Ishikawa M, Biju V. Clathrin-mediated endocytosis of quantum dot-peptide conjugates in living cells. ACS NANO 2009; 3:2419-29. [PMID: 19653641 DOI: 10.1021/nn900663r] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Efficient intracellular delivery of quantum dots (QDs) and unravelling the mechanism underlying the intracellular delivery are essential for advancing the applications of QDs toward in vivo imaging and therapeutic interventions. Here, we show that clathrin-mediated endocytosis is the most important pathway for the intracellular delivery of peptide-conjugated QDs. We selected an insect neuropeptide, namely, allatostatin (AST1, APSGAQRLYG FGL-NH(2)), conjugated it with CdSe-ZnS QDs, and investigated the intracellular delivery of the conjugate in living cells such as human epidermoid ovarian carcinoma cells (A431) and mouse embryonic fibroblast cells (3T3). We selected AST1 to investigate the intracellular delivery of QDs because we recently found it to be efficient for delivering QDs in living mammalian cells. Also, the receptors of AST1 in insects show functional and sequence similarity to G-protein-coupled galanin receptors in mammals. We employed flow cytometry and fluorescence microscopy and investigated the contributions of clathrin-mediated endocytosis, receptor-mediated endocytosis, and charge-based cell penetration or transduction to the intracellular delivery of QD-AST1 conjugates. Interestingly, the intracellular delivery was suppressed by approximately 57% when we inhibited the regulatory enzyme phosphoinositide 3-kinase (PI3K) with wortmannin and blocked the formation of clathrin-coated vesicles. In parallel, we investigated clathrin-mediated endocytosis by colocalizing QD560-labeled clathrin heavy-chain antibody and QD605-AST1. We also estimated galanin receptor-mediated endocytosis of QD-AST1 at <10% by blocking the cells with a galanin antagonist and transduction at <30% by both removing the charge of the peptide due to arginine and suppressing the cell-surface charge due to glycosaminoglycan. In short, the current work shows that multiple pathways are involved in the intracellular delivery of peptide-conjugated QDs, among which clathrin-mediated endocytosis is the most important.
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Affiliation(s)
- Abdulaziz Anas
- Nanobioanalysis Team and Glycolipid Function Analysis Team, Health Technology Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14 Hayashi-Cho, Takamatsu, Kagawa 761-0395, Japan
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Atkin SJ, Griffin BE, Dilworth SM. Polyoma virus and simian virus 40 as cancer models: History and perspectives. Semin Cancer Biol 2009; 19:211-7. [DOI: 10.1016/j.semcancer.2009.03.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2008] [Revised: 02/16/2009] [Accepted: 03/06/2009] [Indexed: 10/21/2022]
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Cheng CK, Fan QW, Weiss WA. PI3K signaling in glioma--animal models and therapeutic challenges. Brain Pathol 2009; 19:112-20. [PMID: 19076776 DOI: 10.1111/j.1750-3639.2008.00233.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The PI3 kinase (PI3K) family plays a complex role in cell biology and metabolism. Signaling through the PI3Ks is frequently activated in many human cancers, including glioblastoma, because of gain-of-function mutations in PIK3CA or loss of PTEN. Experiments involving genetic mouse models and small molecule inhibitors have helped to elucidate the roles of the regulatory and catalytic subunits of PI3K in metabolism and cancer. Downstream of PI3K is Akt, a critical effector of growth, proliferation and survival. The suggested dependence of glioblastoma tumors on PI3K signaling implies that PI3K inhibitors should lead to effective killing of these cancer cells, but that has been shown not to be the case. The engagement of other survival pathways in response to PI3K inhibition prompts the need to develop combination therapies that promote cytotoxicity in cancer cells.
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Affiliation(s)
- Christine K Cheng
- Department of Neurology, University of California, San Francisco, CA 94143, USA.
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How the Rb tumor suppressor structure and function was revealed by the study of Adenovirus and SV40. Virology 2009; 384:274-84. [PMID: 19150725 DOI: 10.1016/j.virol.2008.12.010] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2008] [Accepted: 12/08/2008] [Indexed: 12/14/2022]
Abstract
The review recounts the history of how the study of the DNA tumor viruses including polyoma, SV40 and Adenovirus brought key insights into the structure and function of the Retinoblastoma protein (Rb). Knudsen's model of the two-hit hypothesis to explain patterns of hereditary and sporadic retinoblastoma provided the foundation for the tumor suppressor hypothesis that ultimately led to the cloning of the Rb gene. The discovery that SV40 and Adenovirus could cause tumors when inoculated into animals was startling not only because SV40 had contaminated the poliovirus vaccine and Adenovirus was a common cause of viral induced pneumonia but also because they provided an opportunity to study the genetics and biochemistry of cancer. Studies of mutant forms of these viruses led to the identification of the E1A and Large T antigen (LT) oncogenes and their small transforming elements including the Adenovirus Conserved Regions (CR), the SV40 J domain and the LxCxE motif. The immunoprecipitation studies that initially revealed the size and ultimately the identity of cellular proteins that could bind to these transforming elements were enabled by the widespread development of highly specific monoclonal antibodies against E1A and LT. The identification of Rb as an E1A and LT interacting protein quickly led to the cloning of p107, p130, p300, CBP, p400 and TRRAP and the concept that viral transformation was due, at least in part, to the perturbation of the function of normal cellular proteins. In addition, studies on the ability of E1A to transactivate the Adenovirus E2 promoter led to the cloning of the heterodimeric E2F and DP transcription factor and recognition that Rb repressed transcription of cellular genes required for cell cycle entry and progression. More recent studies have revealed how E1A and LT combine the activity of Rb and the other cellular associated proteins to perturb expression of many genes during viral infection and tumor formation.
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Horiuchi KY, Ma H. Fluorescence polarization and time-resolved fluorescence resonance energy transfer techniques for PI3K assays. Methods Mol Biol 2009; 572:161-176. [PMID: 20694691 DOI: 10.1007/978-1-60761-244-5_10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Fluorescence-based biochemical assays are sensitive and convenient to use; therefore, they are widely employed for enzyme assays and molecular interaction studies. However, when this method is applied for screening of a compound library for drug discovery, high fluorescence compounds, which usually exist in large numbers in chemical libraries, are problematic. Fluorescence Polarization (FP) and Time-Resolved Fluorescence Resonance Energy Transfer (TR-FRET) assays are less affected by compound fluorescence and suitable for large-scale high-throughput screening (HTS). In this section, we describe homogenous FP and TR-FRET methods for PI3-kinase (PI3K), a family of lipid kinases that is "difficult-to-do-HTS" since traditional radioisotope assays are hard to apply to HTS format. The application of FP and TR-FRET techniques for PI3K HTS will be described and advantages and disadvantages of these assays will be discussed.
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Rajala RVS, Wiskur B, Tanito M, Callegan M, Rajala A. Diabetes reduces autophosphorylation of retinal insulin receptor and increases protein-tyrosine phosphatase-1B activity. Invest Ophthalmol Vis Sci 2008; 50:1033-40. [PMID: 19029027 DOI: 10.1167/iovs.08-2851] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
PURPOSE Protein-tyrosine phosphatase-1B (PTP1B) has been implicated in the negative regulation of insulin signaling. The expression, activity, and functional role of PTP1B in the retina are unknown. In this study, the authors examined the relationship between the retinal insulin receptor (IR) and PTP1B in normal and diabetic mouse retinas. METHODS IR and PTP1B localization was examined by immunohistochemistry. The activation of IR was analyzed using specific antibodies against phosphotyrosine. PTP1B activity was determined in anti-PTP1B immunoprecipitates. Glutathione-S-transferase fusion proteins containing wild-type and catalytically inactive mutant PTP1B was used to study the interaction between IR and PTP1B. Anti-IR immunoprecipitates and the cytoplasmic domain of purified IR were incubated in the presence of ATP, and the autophosphorylation of IR with antiphosphotyrosine antibody was analyzed. RESULTS Immunohistochemical analysis of PTP1B shows that it is predominantly expressed in nonphotoreceptor layers of the retina, though it is clearly expressed in the inner segments of the rod photoreceptors. The IR is predominately expressed in rod inner segments. Biochemical analysis of rod outer segments indicates the presence of IR and PTP1B. Retinal IR exhibits a high level of basal autophosphorylation, and this autophosphorylation is reduced in diabetic mouse retinas. In vitro, PTP1B is able to dephosphorylate the autophosphorylated IR. Substrate mutant-trap results indicate a stable interaction between IR and PTP1B. Further, PTP1B activity was increased in diabetic mouse retinas. CONCLUSIONS These studies indicate that diabetes reduces the autophosphorylation of retinal IR and increased PTP1B activity. Further, PTP1B regulates the state of IR phosphorylation in the retina.
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Affiliation(s)
- Raju V S Rajala
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA.
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