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Monteyne AJ, Coelho MOC, Porter C, Abdelrahman DR, Jameson TSO, Finnigan TJA, Stephens FB, Dirks ML, Wall BT. Branched-Chain Amino Acid Fortification Does Not Restore Muscle Protein Synthesis Rates following Ingestion of Lower- Compared with Higher-Dose Mycoprotein. J Nutr 2020; 150:2931-2941. [PMID: 32886108 DOI: 10.1093/jn/nxaa251] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 06/18/2020] [Accepted: 07/29/2020] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND We have shown that ingesting a large bolus (70 g) of the fungal-derived, whole food mycoprotein robustly stimulates muscle protein synthesis (MPS) rates. OBJECTIVE The aim of this study was to determine if a lower dose (35 g) of mycoprotein enriched with branched-chain amino acids (BCAAs) stimulates MPS to the same extent as 70 g of mycoprotein in resistance-trained young men. METHODS Nineteen men [aged 22 ± 1 y, BMI (kg/m2): 25 ± 1] took part in a randomized, double-blind, parallel-group study. Participants received primed, continuous infusions of l-[ring-2H5]phenylalanine and ingested either 70 g mycoprotein (31.5 g protein; MYCO; n = 10) or 35 g BCAA-enriched mycoprotein (18.7 g protein: matched on BCAA content; ENR; n = 9) following a bout of unilateral resistance exercise. Blood and bilateral quadriceps muscle samples were obtained before exercise and protein ingestion and during a 4-h postprandial period to assess MPS in rested and exercised muscle. Two- and 3-factor ANOVAs were used to detect differences in plasma amino acid kinetics and mixed muscle fractional synthetic rates, respectively. RESULTS Postprandial plasma BCAA concentrations increased more rapidly and to a larger degree in ENR compared with MYCO. MPS increased with protein ingestion (P ≤ 0.05) but to a greater extent following MYCO (from 0.025% ± 0.006% to 0.057% ± 0.004% · h-1 in rested muscle, and from 0.024% ± 0.007% to 0.072% ± 0.005% · h-1 in exercised muscle; P < 0.0001) compared with ENR (from 0.031% ± 0.003% to 0.043% ± 0.005% · h-1 in rested muscle, and 0.027% ± 0.005% to 0.052% ± 0.005% · h-1 in exercised muscle; P < 0.01) ingestion. Postprandial MPS rates were greater in MYCO compared with ENR (P < 0.01). CONCLUSIONS The ingestion of lower-dose BCAA-enriched mycoprotein stimulates resting and postexercise MPS rates, but to a lesser extent compared with the ingestion of a BCAA-matched 70-g mycoprotein bolus in healthy young men. This trial was registered at clinicaltrials.gov as 660065600.
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Affiliation(s)
- Alistair J Monteyne
- Department of Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Mariana O C Coelho
- Department of Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Craig Porter
- Department of Surgery, University of Texas Medical Branch, Galveston, TX, USA
| | - Doaa R Abdelrahman
- Department of Surgery, University of Texas Medical Branch, Galveston, TX, USA
| | - Thomas S O Jameson
- Department of Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | | | - Francis B Stephens
- Department of Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Marlou L Dirks
- Department of Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Benjamin T Wall
- Department of Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
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152
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Götting I, Jendrossek V, Matschke J. A New Twist in Protein Kinase B/Akt Signaling: Role of Altered Cancer Cell Metabolism in Akt-Mediated Therapy Resistance. Int J Mol Sci 2020; 21:ijms21228563. [PMID: 33202866 PMCID: PMC7697684 DOI: 10.3390/ijms21228563] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 10/23/2020] [Accepted: 11/09/2020] [Indexed: 12/11/2022] Open
Abstract
Cancer resistance to chemotherapy, radiotherapy and molecular-targeted agents is a major obstacle to successful cancer therapy. Herein, aberrant activation of the phosphatidyl-inositol-3-kinase (PI3K)/protein kinase B (Akt) pathway is one of the most frequently deregulated pathways in cancer cells and has been associated with multiple aspects of therapy resistance. These include, for example, survival under stress conditions, apoptosis resistance, activation of the cellular response to DNA damage and repair of radiation-induced or chemotherapy-induced DNA damage, particularly DNA double strand breaks (DSB). One further important, yet not much investigated aspect of Akt-dependent signaling is the regulation of cell metabolism. In fact, many Akt target proteins are part of or involved in the regulation of metabolic pathways. Furthermore, recent studies revealed the importance of certain metabolites for protection against therapy-induced cell stress and the repair of therapy-induced DNA damage. Thus far, the likely interaction between deregulated activation of Akt, altered cancer metabolism and therapy resistance is not yet well understood. The present review describes the documented interactions between Akt, its target proteins and cancer cell metabolism, focusing on antioxidant defense and DSB repair. Furthermore, the review highlights potential connections between deregulated Akt, cancer cell metabolism and therapy resistance of cancer cells through altered DSB repair and discusses potential resulting therapeutic implications.
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153
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Yang S, Zhang Y, Ting CY, Bettedi L, Kim K, Ghaniam E, Lilly MA. The Rag GTPase Regulates the Dynamic Behavior of TSC Downstream of Both Amino Acid and Growth Factor Restriction. Dev Cell 2020; 55:272-288.e5. [PMID: 32898476 PMCID: PMC7657977 DOI: 10.1016/j.devcel.2020.08.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 06/30/2020] [Accepted: 08/10/2020] [Indexed: 01/09/2023]
Abstract
The dysregulation of the metabolic regulator TOR complex I (TORC1) contributes to a wide array of human pathologies. Tuberous sclerosis complex (TSC) is a potent inhibitor of TORC1. Here, we demonstrate that the Rag GTPase acts in both the amino-acid-sensing and growth factor signaling pathways to control TORC1 activity through the regulation of TSC dynamics in HeLa cells and Drosophila. We find that TSC lysosomal-cytosolic exchange increases in response to both amino acid and growth factor restriction. Moreover, the rate of exchange mirrors TSC function, with depletions of the Rag GTPase blocking TSC lysosomal mobility and rescuing TORC1 activity. Finally, we show that the GATOR2 complex controls the phosphorylation of TSC2, which is essential for TSC exchange. Our data support the model that the amino acid and growth factor signaling pathways converge on the Rag GTPase to inhibit TORC1 activity through the regulation of TSC dynamics.
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Affiliation(s)
- Shu Yang
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yingbiao Zhang
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Chun-Yuan Ting
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Lucia Bettedi
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kuikwon Kim
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Elena Ghaniam
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Mary A Lilly
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
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154
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Yao Y, Hong S, Ikeda T, Mori H, MacDougald OA, Nada S, Okada M, Inoki K. Amino Acids Enhance Polyubiquitination of Rheb and Its Binding to mTORC1 by Blocking Lysosomal ATXN3 Deubiquitinase Activity. Mol Cell 2020; 80:437-451.e6. [PMID: 33157014 PMCID: PMC7665239 DOI: 10.1016/j.molcel.2020.10.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 08/22/2020] [Accepted: 10/02/2020] [Indexed: 01/02/2023]
Abstract
Amino-acid-induced lysosomal mechanistic target of rapamycin complex 1 (mTORC1) localization through the Rag GTPases is a critical step for its activation by Rheb GTPase. However, how the mTORC1 interacts with Rheb on the lysosome remains elusive. We report that amino acids enhance the polyubiquitination of Rheb (Ub-Rheb), which shows a strong binding preference for mTORC1 and supports its activation, while the Ub-Rheb is subjected to subsequent degradation. Mechanistically, we identified ATXN3 as a Ub-Rheb deubiquitinase whose lysosomal localization is blocked by active Rag heterodimer in response to amino acid stimulation. Consistently, cells lacking functional Rag heterodimer on the lysosome accumulate Ub-Rheb, and blockade of its degradation instigates robust lysosomal mTORC1 localization and its activation without the Ragulator-Rag system. Thus, polyubiquitination of Rheb is an important post-translational modification, which facilitates the binding of mTORC1 to Rheb on the lysosome and is another crosstalk between the amino acid and growth factor signaling for mTORC1 activation.
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Affiliation(s)
- Yao Yao
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109-2216, USA
| | - Sungki Hong
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109-2216, USA
| | - Takayuki Ikeda
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109-2216, USA; Department of Biochemistry, Kanazawa Medical University School of Medicine, 1-1 Daigaku, Uchinada, Kahoku-gun, Ishikawa 920-0293, Japan
| | - Hiroyuki Mori
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, 1137 E. Catherine St., Ann Arbor, MI 48109-5622, USA
| | - Ormond A MacDougald
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, 1137 E. Catherine St., Ann Arbor, MI 48109-5622, USA; Department of Internal Medicine, University of Michigan Medical School, 1500 East Medical Center Drive, Ann Arbor, MI 48109-5368, USA
| | - Shigeyuki Nada
- Department of Oncogene Research, the Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Masato Okada
- Department of Oncogene Research, the Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Ken Inoki
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109-2216, USA; Department of Molecular and Integrative Physiology, University of Michigan Medical School, 1137 E. Catherine St., Ann Arbor, MI 48109-5622, USA; Department of Internal Medicine, University of Michigan Medical School, 1500 East Medical Center Drive, Ann Arbor, MI 48109-5368, USA.
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155
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Rubio C, Luna R, Rosiles A, Rubio-Osornio M. Caloric Restriction and Ketogenic Diet Therapy for Epilepsy: A Molecular Approach Involving Wnt Pathway and K ATP Channels. Front Neurol 2020; 11:584298. [PMID: 33250850 PMCID: PMC7676225 DOI: 10.3389/fneur.2020.584298] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Accepted: 09/28/2020] [Indexed: 12/30/2022] Open
Abstract
Epilepsy is a neurological disorder in which, in many cases, there is poor pharmacological control of seizures. Nevertheless, it may respond beneficially to alternative treatments such as dietary therapy, like the ketogenic diet or caloric restriction. One of the mechanisms of these diets is to produce a hyperpolarization mediated by the adenosine triphosphate (ATP)-sensitive potassium (KATP) channels (KATP channels). An extracellular increase of K+ prevents the release of Ca2+ by inhibiting the signaling of the Wnt pathway and the translocation of β-catenin to the cell nucleus. Wnt ligands hyperpolarize the cells by activating K+ current by Ca2+. Each of the diets described in this paper has in common a lower use of carbohydrates, which leads to biochemical, genetic processes presumed to be involved in the reduction of epileptic seizures. Currently, there is not much information about the genetic processes implicated as well as the possible beneficial effects of diet therapy on epilepsy. In this review, we aim to describe some of the possible genes involved in Wnt pathways, their regulation through the KATP channels which are implicated in each one of the diets, and how they can reduce epileptic seizures at the molecular level.
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Affiliation(s)
- Carmen Rubio
- Neurophysiology Department, National Institute of Neurology and Neurosurgery, Manuel Velasco Suárez, Mexico City, Mexico
| | - Rudy Luna
- Neurophysiology Department, National Institute of Neurology and Neurosurgery, Manuel Velasco Suárez, Mexico City, Mexico
| | - Artemio Rosiles
- Experimental Laboratory of Neurodegenerative Diseases, National Institute of Neurology and Neurosurgery, Manuel Velasco Suárez, Mexico City, Mexico
| | - Moisés Rubio-Osornio
- Experimental Laboratory of Neurodegenerative Diseases, National Institute of Neurology and Neurosurgery, Manuel Velasco Suárez, Mexico City, Mexico
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156
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Mirzoev TM. Skeletal Muscle Recovery from Disuse Atrophy: Protein Turnover Signaling and Strategies for Accelerating Muscle Regrowth. Int J Mol Sci 2020; 21:ijms21217940. [PMID: 33114683 PMCID: PMC7663166 DOI: 10.3390/ijms21217940] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 10/08/2020] [Accepted: 10/23/2020] [Indexed: 12/15/2022] Open
Abstract
Skeletal muscle fibers have a unique capacity to adjust their metabolism and phenotype in response to alternations in mechanical loading. Indeed, chronic mechanical loading leads to an increase in skeletal muscle mass, while prolonged mechanical unloading results in a significant decrease in muscle mass (muscle atrophy). The maintenance of skeletal muscle mass is dependent on the balance between rates of muscle protein synthesis and breakdown. While molecular mechanisms regulating protein synthesis during mechanical unloading have been relatively well studied, signaling events implicated in protein turnover during skeletal muscle recovery from unloading are poorly defined. A better understanding of the molecular events that underpin muscle mass recovery following disuse-induced atrophy is of significant importance for both clinical and space medicine. This review focuses on the molecular mechanisms that may be involved in the activation of protein synthesis and subsequent restoration of muscle mass after a period of mechanical unloading. In addition, the efficiency of strategies proposed to improve muscle protein gain during recovery is also discussed.
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Affiliation(s)
- Timur M Mirzoev
- Myology Laboratory, Institute of Biomedical Problems RAS, Moscow 123007, Russia
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157
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Follicle inhibition at the primordial stage without increasing apoptosis, with a combination of everolimus, verapamil. Mol Biol Rep 2020; 47:8711-8726. [PMID: 33079326 DOI: 10.1007/s11033-020-05917-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 10/12/2020] [Indexed: 12/12/2022]
Abstract
The aim of the present study was to test whether inhibition of ovarian primordial follicles and subsequent activation can be achieved by transient mTOR inhibition. In this preclinical investigation, forty-five female immature Wistar rats were randomized in 5 groups. The control group received subcutaneous saline injections. The other groups received Everolimus, Everolimus plus Verapamil, Everolimus plus Fisetin, and Fisetin alone. Primary and secondary outcomes were measured in the left ovary after a treatment period of 8 weeks. Ten days later, animals received 35 IU FSH for 4 days and 35 IU of hCG on the 5th day. The same parameters were examined in the right ovary. AMH, estradiol, and progesterone levels were assessed at the end of both interventions. Significantly, more primordial and less atretic follicles were observed in the Everolimus plus Verapamil group. AMH and progesterone levels were substantially lower in the Everolimus group. Interestingly, after ovarian stimulation higher levels of AMH and progesterone were observed in the Everolimus plus Verapamil group. Immunoblot analysis of ovarian extracts revealed that the administration of Everolimus led to a significant reduction in the mTORC1-mediated phosphorylation of the 70-kDa ribosomal protein S6 kinase 1. This decrease was reversed in the presence of FSH after stopping drug administration. The expression of the anti-apoptotic molecule Bcl2 as well as of LC3-II and ATG12 was increased after removal of the Everolimus plus Verapamil combination, indicating reduced apoptosis and increased autophagy, whereas the levels of the proliferation marker PCNA in the granulosa cells were elevated, consistent with initiation of follicular growth.Thus, the combination of Everolimus plus Verapamil is capable of increasing the number of competent primordial follicles while reducing atresia.
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158
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Water Extract of Lotus Leaf Alleviates Dexamethasone-Induced Muscle Atrophy via Regulating Protein Metabolism-Related Pathways in Mice. Molecules 2020; 25:molecules25204592. [PMID: 33050143 PMCID: PMC7587191 DOI: 10.3390/molecules25204592] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 09/30/2020] [Accepted: 10/02/2020] [Indexed: 12/17/2022] Open
Abstract
Muscle atrophy is an abnormal condition characterized by loss of skeletal muscle mass and function and is primarily caused by injury, malnutrition, various diseases, and aging. Leaf of lotus (Nelumbo nucifera Gaertn), which has been used for medicinal purposes, contains various active ingredients, including polyphenols, and is reported to exert an antioxidant effect. In this study, we investigated the effect of water extract of lotus leaf (LL) on muscle atrophy and the underlying molecular mechanisms of action. Amounts of 100, 200, or 300 mg/kg/day LL were administered to dexamethasone (DEX)-induced muscle atrophy mice for 4 weeks. Micro-computed tomography (CT) analysis revealed that the intake of LL significantly increased calf muscle volume, surface area, and density in DEX-induced muscle atrophy mice. Administration of LL recovered moving distance, grip strength, ATP production, and body weight, which were decreased by DEX. In addition, muscle damage caused by DEX was also improved by LL. LL reduced the protein catabolic pathway by suppressing gene expression of muscle atrophy F-Box (MAFbx; atrogin-1), muscle RING finger 1 (MuRF1), and forkhead box O (FoxO)3a, as well as phosphorylation of AMP-activated kinase (AMPK). The AKT-mammalian target of the rapamycin (mTOR) signal pathway, which is important for muscle protein synthesis, was increased in LL-administered groups. The HPLC analysis and pharmacological test revealed that quercetin 3-O-beta-glucuronide (Q3G) is a major active component in LL. Thus, Q3G decreased the gene expression of atrogin-1 and MuRF1 and phosphorylation of AMPK. This compound also increased phosphorylation levels of mTOR and its upstream enzyme AKT in DEX-treated C2C12 cells. We identified that LL improves muscle wasting through regulation of muscle protein metabolism in DEX-induced muscle atrophy mice. Q3G is predicted to be one of the major active phenolic components in LL. Therefore, we propose LL as a supplement or therapeutic agent to prevent or treat muscle wasting, such as sarcopenia.
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159
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CDK 4/6 Inhibition Overcomes Acquired and Inherent Resistance to PI3Kα Inhibition in Pre-Clinical Models of Head and Neck Squamous Cell Carcinoma. J Clin Med 2020; 9:jcm9103214. [PMID: 33036331 PMCID: PMC7601167 DOI: 10.3390/jcm9103214] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 09/24/2020] [Accepted: 10/02/2020] [Indexed: 12/28/2022] Open
Abstract
Activating alterations in PIK3CA, the gene coding for the catalytic subunit of phosphoinositide-3-kinase (PI3K), are prevalent in head and neck squamous cell carcinoma (HNSCC) and thought to be one of the main drivers of these tumors. However, early clinical trials on PI3K inhibitors (PI3Ki) have been disappointing due to the limited durability of the activity of these drugs. To investigate the resistance mechanisms to PI3Ki and attempt to overcome them, we conducted a molecular-based study using both HNSCC cell lines and patient-derived xenografts (PDXs). We sought to simulate and dissect the molecular pathways that come into play in PIK3CA-altered HNSCC treated with isoform-specific PI3Ki (BYL719, GDC0032). In vitro assays of cell viability and protein expression indicate that activation of the mTOR and cyclin D1 pathways is associated with resistance to PI3Ki. Specifically, in BYL719-resistant cells, BYL719 treatment did not induce pS6 and pRB inhibition as detected in BYL719-sensitive cells. By combining PI3Ki with either mammalian target of rapamycin complex 1 (mTORC1) or cyclin D1 kinase (CDK) 4/6 specific inhibitors (RAD001 and abemaciclib, respectively), we were able to overcome the acquired resistance. Furthermore, we found that PI3Ki and CDK 4/6 inhibitors have a synergistic anti-tumor effect when combined in human papillomavirus (HPV)-negative/PIK3CA-WT tumors. These findings provide a rationale for combining PI3Ki and CDK 4/6 inhibitors to enhance anti-tumor efficacy in HNSCC patients.
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160
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Texada MJ, Koyama T, Rewitz K. Regulation of Body Size and Growth Control. Genetics 2020; 216:269-313. [PMID: 33023929 PMCID: PMC7536854 DOI: 10.1534/genetics.120.303095] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 06/29/2020] [Indexed: 12/20/2022] Open
Abstract
The control of body and organ growth is essential for the development of adults with proper size and proportions, which is important for survival and reproduction. In animals, adult body size is determined by the rate and duration of juvenile growth, which are influenced by the environment. In nutrient-scarce environments in which more time is needed for growth, the juvenile growth period can be extended by delaying maturation, whereas juvenile development is rapidly completed in nutrient-rich conditions. This flexibility requires the integration of environmental cues with developmental signals that govern internal checkpoints to ensure that maturation does not begin until sufficient tissue growth has occurred to reach a proper adult size. The Target of Rapamycin (TOR) pathway is the primary cell-autonomous nutrient sensor, while circulating hormones such as steroids and insulin-like growth factors are the main systemic regulators of growth and maturation in animals. We discuss recent findings in Drosophila melanogaster showing that cell-autonomous environment and growth-sensing mechanisms, involving TOR and other growth-regulatory pathways, that converge on insulin and steroid relay centers are responsible for adjusting systemic growth, and development, in response to external and internal conditions. In addition to this, proper organ growth is also monitored and coordinated with whole-body growth and the timing of maturation through modulation of steroid signaling. This coordination involves interorgan communication mediated by Drosophila insulin-like peptide 8 in response to tissue growth status. Together, these multiple nutritional and developmental cues feed into neuroendocrine hubs controlling insulin and steroid signaling, serving as checkpoints at which developmental progression toward maturation can be delayed. This review focuses on these mechanisms by which external and internal conditions can modulate developmental growth and ensure proper adult body size, and highlights the conserved architecture of this system, which has made Drosophila a prime model for understanding the coordination of growth and maturation in animals.
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Affiliation(s)
| | - Takashi Koyama
- Department of Biology, University of Copenhagen, 2100, Denmark
| | - Kim Rewitz
- Department of Biology, University of Copenhagen, 2100, Denmark
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161
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Chao X, Qian H, Wang S, Fulte S, Ding WX. Autophagy and liver cancer. Clin Mol Hepatol 2020; 26:606-617. [PMID: 33053934 PMCID: PMC7641568 DOI: 10.3350/cmh.2020.0169] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 07/31/2020] [Accepted: 08/01/2020] [Indexed: 02/07/2023] Open
Abstract
Autophagy is a highly conserved catabolic process that degrades cytosolic proteins and organelles via formation of autophagosomes that fuse with lysosomes to form autolysosomes, whereby autophagic cargos are degraded. Numerous studies have demonstrated that autophagy plays a critical role in the regulation of liver physiology and homeostasis, and impaired autophagy leads to the pathogenesis of various liver diseases such as viral hepatitis, alcohol associated liver diseases (AALD), non-alcoholic fatty liver diseases (NAFLD), and liver cancer. Recent evidence indicates that autophagy may play a dual role in liver cancer: inhibiting early tumor initiation while promoting progression and malignancy of already formed liver tumors. In this review, we summarized the progress of current understanding of how hepatic viral infection, alcohol consumption and diet-induced fatty liver diseases impair hepatic autophagy. We also discussed how impaired autophagy promotes liver tumorigenesis, and paradoxically how autophagy is required to promote the malignancy and progression of liver cancer. Understanding the molecular mechanisms underlying how autophagy differentially affects liver cancer development and progression may help to design better therapeutic strategies for prevention and treatment of liver cancer.
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Affiliation(s)
- Xiaojuan Chao
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS, USA
| | - Hui Qian
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS, USA
| | - Shaogui Wang
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS, USA
| | - Sam Fulte
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS, USA
| | - Wen-Xing Ding
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS, USA
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162
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Mukhtar I. Inflammatory and immune mechanisms underlying epileptogenesis and epilepsy: From pathogenesis to treatment target. Seizure 2020; 82:65-79. [PMID: 33011590 DOI: 10.1016/j.seizure.2020.09.015] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 09/15/2020] [Accepted: 09/17/2020] [Indexed: 02/06/2023] Open
Abstract
Epilepsy is a brain disease associated with epileptic seizures as well as with neurobehavioral outcomes of this condition. In the last century, inflammation emerged as a crucial factor in epilepsy etiology. Various brain insults through activation of neuronal and non-neuronal brain cells initiate a series of inflammatory events. Growing observations strongly suggest that abnormal activation of critical inflammatory processes contributes to epileptogenesis, a gradual process by which a normal brain transforms into the epileptic brain. Increased knowledge of inflammatory pathways in epileptogenesis has unveiled mechanistic targets for novel antiepileptic therapies. Molecules specifically targeting the pivotal inflammatory pathways may serve as promising candidates to halt the development of epilepsy. The present paper reviews the pieces of evidence conceptually supporting the potential role of inflammatory mechanisms and the relevant blood-brain barrier (BBB) disruption in epileptogenesis. Also, it discusses the mechanisms underlying inflammation-induced neuronal-glial network impairment and highlights innovative neuroregulatory actions of typical inflammatory molecules. Finally, it presents a brief analysis of observations supporting the therapeutic role of inflammation-targeting tiny molecules in epileptic seizures.
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Affiliation(s)
- Iqra Mukhtar
- H.E.J Research Institute of Chemistry, International Center For Chemical and Biological Sciences, University of Karachi, Karachi, 75270, Pakistan; Department of Pharmacology, Faculty of Pharmacy and Pharmaceutical Sciences, University of Karachi, Karachi, 75270, Pakistan.
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163
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Wei C, Pan Y, Zhang Y, Dai Y, Jiang L, Shi L, Yang W, Xu S, Zhang Y, Xu W, Zhang Y, Lin X, Zhang S. Overactivated sonic hedgehog signaling aggravates intrauterine adhesion via inhibiting autophagy in endometrial stromal cells. Cell Death Dis 2020; 11:755. [PMID: 32934215 PMCID: PMC7492405 DOI: 10.1038/s41419-020-02956-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 08/17/2020] [Accepted: 08/27/2020] [Indexed: 02/07/2023]
Abstract
Autophagy can be dynamically induced in response to stresses and is an essential, ubiquitous intracellular recycling system that impacts the fate of damaged resident cells, thereby influencing wound healing. Endometrial fibrosis is a form of abnormal wound healing that causes intrauterine adhesion (IUA) and infertility. We previously demonstrated that overactivated sonic hedgehog (SHH) signaling exacerbated endometrial fibrosis, but the role of autophagy in this process is still unknown. Here, we report that impaired autophagy participates in SHH pathway-induced endometrial fibrosis. Endometrial stroma-myofibroblast transition accompanied by autophagy dysfunction was present in both endometrial biopsies of IUA patients and Amhr2cre/+R26-SmoM2+/− (AM2) transgenic mouse. Mechanistically, SHH pathway negatively regulated autophagy through pAKT-mTORC1 in a human endometrial stromal cell line (T-HESCs). Furthermore, SHH pathway-mediated fibrosis was partly counteracted by autophagy modulation in both T-HESCs and the murine IUA model. Specifically, the impact of SHH pathway inhibition (GANT61) was reversed by the pharmacological autophagy inhibitor chloroquine (CQ) or RNA interference of autophagy-related gene ATG5 or ATG7. Similar results were obtained from the murine IUA model treated with GANT61 and CQ. Moreover, promoting autophagy with rapamycin reduced fibrosis in the AM2 IUA model to baseline levels. In summary, defective autophagy is involved in SHH pathway-driven endometrial fibrosis, suggesting a potential novel molecular target for IUA treatment.
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Affiliation(s)
- Cheng Wei
- Assisted Reproduction Unit, Department of Obstetrics and Gynecology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, 310016, China.,Key Laboratory of Reproductive Dysfunction Management of Zhejiang Province, No. 3 Qingchun East Road, Jianggan District, Hangzhou, 310016, China
| | - Yibin Pan
- Assisted Reproduction Unit, Department of Obstetrics and Gynecology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, 310016, China.,Key Laboratory of Reproductive Dysfunction Management of Zhejiang Province, No. 3 Qingchun East Road, Jianggan District, Hangzhou, 310016, China
| | - Yinli Zhang
- Assisted Reproduction Unit, Department of Obstetrics and Gynecology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, 310016, China.,Key Laboratory of Reproductive Dysfunction Management of Zhejiang Province, No. 3 Qingchun East Road, Jianggan District, Hangzhou, 310016, China
| | - Yongdong Dai
- Assisted Reproduction Unit, Department of Obstetrics and Gynecology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, 310016, China.,Key Laboratory of Reproductive Dysfunction Management of Zhejiang Province, No. 3 Qingchun East Road, Jianggan District, Hangzhou, 310016, China
| | - Lingling Jiang
- Assisted Reproduction Unit, Department of Obstetrics and Gynecology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, 310016, China.,Key Laboratory of Reproductive Dysfunction Management of Zhejiang Province, No. 3 Qingchun East Road, Jianggan District, Hangzhou, 310016, China
| | - Libing Shi
- Assisted Reproduction Unit, Department of Obstetrics and Gynecology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, 310016, China.,Key Laboratory of Reproductive Dysfunction Management of Zhejiang Province, No. 3 Qingchun East Road, Jianggan District, Hangzhou, 310016, China
| | - Weijie Yang
- Assisted Reproduction Unit, Department of Obstetrics and Gynecology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, 310016, China.,Key Laboratory of Reproductive Dysfunction Management of Zhejiang Province, No. 3 Qingchun East Road, Jianggan District, Hangzhou, 310016, China
| | - Shiqian Xu
- Assisted Reproduction Unit, Department of Obstetrics and Gynecology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, 310016, China.,Key Laboratory of Reproductive Dysfunction Management of Zhejiang Province, No. 3 Qingchun East Road, Jianggan District, Hangzhou, 310016, China
| | - Yingyi Zhang
- Assisted Reproduction Unit, Department of Obstetrics and Gynecology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, 310016, China.,Key Laboratory of Reproductive Dysfunction Management of Zhejiang Province, No. 3 Qingchun East Road, Jianggan District, Hangzhou, 310016, China
| | - Wenzhi Xu
- Assisted Reproduction Unit, Department of Obstetrics and Gynecology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, 310016, China.,Key Laboratory of Reproductive Dysfunction Management of Zhejiang Province, No. 3 Qingchun East Road, Jianggan District, Hangzhou, 310016, China
| | - Yanling Zhang
- Assisted Reproduction Unit, Department of Obstetrics and Gynecology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, 310016, China.,Key Laboratory of Reproductive Dysfunction Management of Zhejiang Province, No. 3 Qingchun East Road, Jianggan District, Hangzhou, 310016, China
| | - Xiaona Lin
- Assisted Reproduction Unit, Department of Obstetrics and Gynecology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, 310016, China. .,Key Laboratory of Reproductive Dysfunction Management of Zhejiang Province, No. 3 Qingchun East Road, Jianggan District, Hangzhou, 310016, China.
| | - Songying Zhang
- Assisted Reproduction Unit, Department of Obstetrics and Gynecology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, 310016, China. .,Key Laboratory of Reproductive Dysfunction Management of Zhejiang Province, No. 3 Qingchun East Road, Jianggan District, Hangzhou, 310016, China.
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164
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Malarkannan S. Molecular mechanisms of FasL-mediated 'reverse-signaling'. Mol Immunol 2020; 127:31-37. [PMID: 32905906 DOI: 10.1016/j.molimm.2020.08.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 08/15/2020] [Accepted: 08/21/2020] [Indexed: 02/07/2023]
Abstract
Effector lymphocytes, including NK and T cells, express FasL. Expression of Fas, the receptor for FasL in tumor cells, renders them susceptible to NK and T cell-mediated killing. The functional relevance of FasL in initiating death signals in tumor cells is well-characterized. However, the cytoplasmic interacting partners and the potential signaling pathways downstream of FasL are far from fully defined. FasL possesses an 81 amino acid long cytoplasmic tail with multiple unique recruitment motifs. We predict multiple interdependent signaling complexes form the core of the 'reverse signaling' downstream of FasL. A direct interaction between the proline-rich domain of FasL and the SH3 domain of PI(3)K-p85α initiates the first pathway. This cascade helps FasL to link to PLC-γ2 via PIP3 or the Akt-dependent activation of mTOR complexes. Independently, a GRB2/GADs-binding PXXP cytoplasmic motif of FasL can initiate a Ras-GTP-dependent PAK1→C-Raf→MEK1/2→ERK1/2 activation. FasL can recruit Fyn via the proline-rich domain leading to the recruitment of ADAP. Through its ability to directly interact with Carma1 and TAK1, ADAP initiates the formation of the Carma1/Bcl10/Malt1-based CBM signalosome that is primarily responsible for inflammatory cytokine production. Here, we explore the conserved cytoplasmic domains of FasL, the potential signaling molecules that interact, and the functional downstream consequences within the effector lymphocytes to define the FasL-mediated 'reverse signaling'.
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Affiliation(s)
- Subramaniam Malarkannan
- Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, WI, United States; Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, United States; Department of Medicine, Medical College of Wisconsin, Milwaukee, WI, United States; Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, United States.
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165
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Qi S, Sun X, Choi HK, Yao J, Wang L, Wu G, He Y, Pan J, Guan JL, Liu F. FAK Promotes Early Osteoprogenitor Cell Proliferation by Enhancing mTORC1 Signaling. J Bone Miner Res 2020; 35:1798-1811. [PMID: 32286710 PMCID: PMC7486225 DOI: 10.1002/jbmr.4029] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 03/16/2020] [Accepted: 04/05/2020] [Indexed: 02/05/2023]
Abstract
Focal adhesion kinase (FAK) has important functions in bone homeostasis but its role in early osteoprogenitor cells is unknown. We show herein that mice lacking FAK in Dermo1-expressing cells exhibited low bone mass and decreased osteoblast number. Mechanistically, FAK-deficient early osteoprogenitor cells had decreased proliferation and significantly reduced mammalian/mechanistic target of rapamycin complex 1 (mTORC1) signaling, a central regulator of cell growth and proliferation. Furthermore, our data showed that the pharmacological inhibition of FAK kinase-dependent function alone was sufficient to decrease the proliferation and compromise the mineralization of early osteoprogenitor cells. In contrast to the Fak deletion in early osteoprogenitor cells, FAK loss in Col3.6 Cre-targeted osteoblasts did not cause bone loss, and Fak deletion in osteoblasts did not affect proliferation, differentiation, and mTORC1 signaling but increased the level of active proline-rich tyrosine kinase 2 (PYK2), which belongs to the same non-receptor tyrosine kinase family as FAK. Importantly, mTORC1 signaling in bone marrow stromal cells (BMSCs) was reduced if FAK kinase was inhibited at the early osteogenic differentiation stage. In contrast, mTORC1 signaling in BMSCs was not affected if FAK kinase was inhibited at a later osteogenic differentiation stage, in which, however, the concomitant inhibition of both FAK kinase and PYK2 kinase reduced mTORC1 signaling. In summary, our data suggest that FAK promotes early osteoprogenitor cell proliferation by enhancing mTORC1 signaling via its kinase-dependent function and the loss of FAK in osteoblasts can be compensated by the upregulated active PYK2. © 2020 American Society for Bone and Mineral Research.
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Affiliation(s)
- Shuqun Qi
- State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, China.,National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China.,Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China.,Department of Biologic and Materials Sciences and Prosthodontics, University of Michigan School of Dentistry, Ann Arbor, MI, USA
| | - Xiumei Sun
- Department of Biologic and Materials Sciences and Prosthodontics, University of Michigan School of Dentistry, Ann Arbor, MI, USA.,Department of Orthodontics, Jilin University School and Hospital of Stomatology, Changchun, China
| | - Han Kyoung Choi
- Department of Biologic and Materials Sciences and Prosthodontics, University of Michigan School of Dentistry, Ann Arbor, MI, USA
| | - Jinfeng Yao
- Department of Biologic and Materials Sciences and Prosthodontics, University of Michigan School of Dentistry, Ann Arbor, MI, USA.,Department of Stomatology, The Second People's Hospital of Shenzhen, Shenzhen, China
| | - Li Wang
- Department of Biologic and Materials Sciences and Prosthodontics, University of Michigan School of Dentistry, Ann Arbor, MI, USA
| | - Guomin Wu
- Department of Biologic and Materials Sciences and Prosthodontics, University of Michigan School of Dentistry, Ann Arbor, MI, USA.,Department of Orthodontics, Jilin University School and Hospital of Stomatology, Changchun, China
| | - Yun He
- Department of Biologic and Materials Sciences and Prosthodontics, University of Michigan School of Dentistry, Ann Arbor, MI, USA.,Dental Department, College of Medicine, Chengdu University, Chengdu, China
| | - Jian Pan
- State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, China.,National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China.,Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Jun-Lin Guan
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Fei Liu
- Department of Biologic and Materials Sciences and Prosthodontics, University of Michigan School of Dentistry, Ann Arbor, MI, USA
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166
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Pierrevelcin M, Fuchs Q, Lhermitte B, Messé M, Guérin E, Weingertner N, Martin S, Lelong-Rebel I, Nazon C, Dontenwill M, Entz-Werlé N. Focus on Hypoxia-Related Pathways in Pediatric Osteosarcomas and Their Druggability. Cells 2020; 9:cells9091998. [PMID: 32878021 PMCID: PMC7564372 DOI: 10.3390/cells9091998] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 08/21/2020] [Accepted: 08/22/2020] [Indexed: 12/17/2022] Open
Abstract
Osteosarcoma is the most frequent primary bone tumor diagnosed during adolescence and young adulthood. It is associated with the worst outcomes in the case of poor response to chemotherapy and in metastatic disease. While no molecular biomarkers are clearly and currently associated with those worse situations, the study of pathways involved in the high level of tumor necrosis and in the immune/metabolic intra-tumor environment seems to be a way to understand these resistant and progressive osteosarcomas. In this review, we provide an updated overview of the role of hypoxia in osteosarcoma oncogenesis, progression and during treatment. We describe the role of normoxic/hypoxic environment in normal tissues, bones and osteosarcomas to understand their role and to estimate their druggability. We focus particularly on the role of intra-tumor hypoxia in osteosarcoma cell resistance to treatments and its impact in its endogenous immune component. Together, these previously published observations conduct us to present potential perspectives on the use of therapies targeting hypoxia pathways. These therapies could afford new treatment approaches in this bone cancer. Nevertheless, to study the osteosarcoma cell druggability, we now need specific in vitro models closely mimicking the tumor, its intra-tumor hypoxia and the immune microenvironment to more accurately predict treatment efficacy and be complementary to mouse models.
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Affiliation(s)
- Marina Pierrevelcin
- Laboratory of Bioimaging and Pathologies, UMR CNRS 7021, 67405 Illkirch, France; (M.P.); (Q.F.); (B.L.); (M.M.); (S.M.); (I.L.-R.); (M.D.)
| | - Quentin Fuchs
- Laboratory of Bioimaging and Pathologies, UMR CNRS 7021, 67405 Illkirch, France; (M.P.); (Q.F.); (B.L.); (M.M.); (S.M.); (I.L.-R.); (M.D.)
| | - Benoit Lhermitte
- Laboratory of Bioimaging and Pathologies, UMR CNRS 7021, 67405 Illkirch, France; (M.P.); (Q.F.); (B.L.); (M.M.); (S.M.); (I.L.-R.); (M.D.)
- Pathology Department, University Hospital of Strasbourg, 67098 Strasbourg, France;
| | - Melissa Messé
- Laboratory of Bioimaging and Pathologies, UMR CNRS 7021, 67405 Illkirch, France; (M.P.); (Q.F.); (B.L.); (M.M.); (S.M.); (I.L.-R.); (M.D.)
| | - Eric Guérin
- Oncobiology, Laboratory of Biochemistry and Molecular Biology, University Hospital of Strasbourg, 67098 Strasbourg, France;
| | - Noelle Weingertner
- Pathology Department, University Hospital of Strasbourg, 67098 Strasbourg, France;
| | - Sophie Martin
- Laboratory of Bioimaging and Pathologies, UMR CNRS 7021, 67405 Illkirch, France; (M.P.); (Q.F.); (B.L.); (M.M.); (S.M.); (I.L.-R.); (M.D.)
| | - Isabelle Lelong-Rebel
- Laboratory of Bioimaging and Pathologies, UMR CNRS 7021, 67405 Illkirch, France; (M.P.); (Q.F.); (B.L.); (M.M.); (S.M.); (I.L.-R.); (M.D.)
| | - Charlotte Nazon
- Pediatric Oncohematology Unit, University Hospital of Strasbourg, 67098 Strasbourg, France;
| | - Monique Dontenwill
- Laboratory of Bioimaging and Pathologies, UMR CNRS 7021, 67405 Illkirch, France; (M.P.); (Q.F.); (B.L.); (M.M.); (S.M.); (I.L.-R.); (M.D.)
| | - Natacha Entz-Werlé
- Laboratory of Bioimaging and Pathologies, UMR CNRS 7021, 67405 Illkirch, France; (M.P.); (Q.F.); (B.L.); (M.M.); (S.M.); (I.L.-R.); (M.D.)
- Pediatric Oncohematology Unit, University Hospital of Strasbourg, 67098 Strasbourg, France;
- Correspondence: ; Tel.: +33-3-8812-8396; Fax: +33-3-8812-8092
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167
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Natarajan N, Thiruvenkatam V. An Insight of Scientific Developments in TSC for Better Therapeutic Strategy. Curr Top Med Chem 2020; 20:2080-2093. [PMID: 32842942 DOI: 10.2174/1568026620666200825170355] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 06/15/2020] [Accepted: 07/20/2020] [Indexed: 11/22/2022]
Abstract
Tuberous sclerosis complex (TSC) is a rare genetic disease, which is characterized by noncancerous tumors in multi-organ systems in the body. Mutations in the TSC1 or TSC2 genes are known to cause the disease. The resultant mutant proteins TSC1 (hamartin) and TSC2 (tuberin) complex evade its normal tumor suppressor function, which leads to abnormal cell growth and proliferation. Both TSC1 and TSC2 are involved in several protein-protein interactions, which play a significant role in maintaining cellular homeostasis. The recent biochemical, genetic, structural biology, clinical and drug discovery advancements on TSC give a useful insight into the disease as well as the molecular aspects of TSC1 and TSC2. The complex nature of TSC disease, a wide range of manifestations, mosaicism and several other factors limits the treatment choices. This review is a compilation of the course of TSC, starting from its discovery to the current findings that would take us a step ahead in finding a cure for TSC.
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Affiliation(s)
- Nalini Natarajan
- Discipline of Biological Engineering, Indian Institute of Technology Gandhinagar, Gujarat-382355, India
| | - Vijay Thiruvenkatam
- Discipline of Biological Engineering, Indian Institute of Technology Gandhinagar, Gujarat-382355, India
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168
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Castets P, Ham DJ, Rüegg MA. The TOR Pathway at the Neuromuscular Junction: More Than a Metabolic Player? Front Mol Neurosci 2020; 13:162. [PMID: 32982690 PMCID: PMC7485269 DOI: 10.3389/fnmol.2020.00162] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 08/05/2020] [Indexed: 12/18/2022] Open
Abstract
The neuromuscular junction (NMJ) is the chemical synapse connecting motor neurons and skeletal muscle fibers. NMJs allow all voluntary movements, and ensure vital functions like breathing. Changes in the structure and function of NMJs are hallmarks of numerous pathological conditions that affect muscle function including sarcopenia, the age-related loss of muscle mass and function. However, the molecular mechanisms leading to the morphological and functional perturbations in the pre- and post-synaptic compartments of the NMJ remain poorly understood. Here, we discuss the role of the metabolic pathway associated to the kinase TOR (Target of Rapamycin) in the development, maintenance and alterations of the NMJ. This is of particular interest as the TOR pathway has been implicated in aging, but its role at the NMJ is still ill-defined. We highlight the respective functions of the two TOR-associated complexes, TORC1 and TORC2, and discuss the role of localized protein synthesis and autophagy regulation in motor neuron terminals and sub-synaptic regions of muscle fibers and their possible effects on NMJ maintenance.
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Affiliation(s)
- Perrine Castets
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland
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169
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Melick CH, Jewell JL. Regulation of mTORC1 by Upstream Stimuli. Genes (Basel) 2020; 11:genes11090989. [PMID: 32854217 PMCID: PMC7565831 DOI: 10.3390/genes11090989] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/22/2020] [Accepted: 08/23/2020] [Indexed: 01/08/2023] Open
Abstract
The mammalian target of rapamycin (mTOR) is an evolutionary conserved Ser/Thr protein kinase that senses multiple upstream stimuli to control cell growth, metabolism, and autophagy. mTOR is the catalytic subunit of mTOR complex 1 (mTORC1). A significant amount of research has uncovered the signaling pathways regulated by mTORC1, and the involvement of these signaling cascades in human diseases like cancer, diabetes, and ageing. Here, we review advances in mTORC1 regulation by upstream stimuli. We specifically focus on how growth factors, amino acids, G-protein coupled receptors (GPCRs), phosphorylation, and small GTPases regulate mTORC1 activity and signaling.
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Affiliation(s)
- Chase H. Melick
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA;
- Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jenna L. Jewell
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA;
- Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Correspondence:
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170
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Lu Y, Zhang EY, Liu J, Yu JJ. Inhibition of the mechanistic target of rapamycin induces cell survival via MAPK in tuberous sclerosis complex. Orphanet J Rare Dis 2020; 15:209. [PMID: 32807195 PMCID: PMC7433150 DOI: 10.1186/s13023-020-01490-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 08/05/2020] [Indexed: 01/29/2023] Open
Abstract
Background Tuberous sclerosis complex (TSC) is a genetic disorder that cause tumors to form in many organs. These lesions may lead to epilepsy, autism, developmental delay, renal, and pulmonary failure. Loss of function mutations in TSC1 and TSC2 genes by aberrant activation of the mechanistic target of rapamycin (mTORC1) signaling pathway are the known causes of TSC. Therefore, targeting mTORC1 becomes a most available therapeutic strategy for TSC. Although mTORC1 inhibitor rapamycin and Rapalogs have demonstrated exciting results in the recent clinical trials, however, tumors rebound and upon the discontinuation of the mTORC1 inhibition. Thus, understanding the underlying molecular mechanisms responsible for rapamycin-induced cell survival becomes an urgent need. Identification of additional molecular targets and development more effective remission-inducing therapeutic strategies are necessary for TSC patients. Results We have discovered an Mitogen-activated protein kinase (MAPK)-evoked positive feedback loop that dampens the efficacy of mTORC1 inhibition. Mechanistically, mTORC1 inhibition increased MEK1-dependent activation of MAPK in TSC-deficient cells. Pharmacological inhibition of MAPK abrogated this feedback loop activation. Importantly, the combinatorial inhibition of mTORC1 and MAPK induces the death of TSC2-deficient cells. Conclusions Our results provide a rationale for dual targeting of mTORC1 and MAPK pathways in TSC and other mTORC1 hyperactive neoplasm.
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Affiliation(s)
- Yiyang Lu
- Department of Internal Medicine, Pulmonary, Critical Care and Sleep Medicine, University of Cincinnati College of Medicine, 231 Albert Sabin Way-ML 0564, Cincinnati, OH, 45267, USA
| | - Erik Y Zhang
- Department of Internal Medicine, Pulmonary, Critical Care and Sleep Medicine, University of Cincinnati College of Medicine, 231 Albert Sabin Way-ML 0564, Cincinnati, OH, 45267, USA
| | - Jie Liu
- Department of Internal Medicine, Pulmonary, Critical Care and Sleep Medicine, University of Cincinnati College of Medicine, 231 Albert Sabin Way-ML 0564, Cincinnati, OH, 45267, USA.,Department of Pulmonary and Critical Care Medicine, Guangzhou Institute for Respiratory Health, State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Jane J Yu
- Department of Internal Medicine, Pulmonary, Critical Care and Sleep Medicine, University of Cincinnati College of Medicine, 231 Albert Sabin Way-ML 0564, Cincinnati, OH, 45267, USA.
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171
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Choi S, Kim H. The Remedial Potential of Lycopene in Pancreatitis through Regulation of Autophagy. Int J Mol Sci 2020; 21:ijms21165775. [PMID: 32806545 PMCID: PMC7460830 DOI: 10.3390/ijms21165775] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 08/05/2020] [Accepted: 08/11/2020] [Indexed: 12/12/2022] Open
Abstract
Autophagy is an evolutionarily conserved process that degrades damaged organelles and recycles macromolecules to support cell survival. However, in certain disease states, dysregulated autophagy can play an important role in cell death. In pancreatitis, the accumulation of autophagic vacuoles and damaged mitochondria and premature activation of trypsinogen are shown in pancreatic acinar cells (PACs), which are the hallmarks of impaired autophagy. Oxidative stress mediates inflammatory signaling and cytokine expression in PACs, and it also causes mitochondrial dysfunction and dysregulated autophagy. Thus, oxidative stress may be a mediator for autophagic impairment in pancreatitis. Lycopene is a natural pigment that contributes to the red color of fruits and vegetables. Due to its antioxidant activity, it inhibited oxidative stress-induced expression of cytokines in experimental models of acute pancreatitis. Lycopene reduces cell death through the activation of 5′-AMP-activated protein kinase-dependent autophagy in certain cells. Therefore, lycopene may ameliorate pancreatitis by preventing oxidative stress-induced impairment of autophagy and/or by directly activating autophagy in PACs.
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172
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Parsons R. Discovery of the PTEN Tumor Suppressor and Its Connection to the PI3K and AKT Oncogenes. Cold Spring Harb Perspect Med 2020; 10:a036129. [PMID: 31932465 PMCID: PMC7397838 DOI: 10.1101/cshperspect.a036129] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PTEN (phosphatase and tensin homolog on chromosome 10) was discovered over 20 years ago in 1997 and linked to the phosphatidylinositol 3-kinase (PI3K) and AKT oncogenes the following year. The discovery of PTEN emerged from the linked concepts of oncogenes and tumor suppressor genes that cause and prevent cancer and the fields of tumor viruses and human cancer genetics from which these two concepts arose. While much has been learned since, the initial discovery and characterization, including the discovery that PTEN is a regulator of PI3K and AKT, provide the foundation on which we continue to build our knowledge. To provide the context in which these cancer genes were discovered, background information that led to their discovery will also be discussed, which will hopefully be a useful guide for readers seeking to build on the work of others.
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Affiliation(s)
- Ramon Parsons
- Department of Oncological Sciences, Tisch Cancer Institute at Mount Sinai, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
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173
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Maity S, Das F, Kasinath BS, Ghosh-Choudhury N, Ghosh Choudhury G. TGFβ acts through PDGFRβ to activate mTORC1 via the Akt/PRAS40 axis and causes glomerular mesangial cell hypertrophy and matrix protein expression. J Biol Chem 2020; 295:14262-14278. [PMID: 32732288 DOI: 10.1074/jbc.ra120.014994] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 07/27/2020] [Indexed: 12/21/2022] Open
Abstract
Interaction of transforming growth factor-β (TGFβ)-induced canonical signaling with the noncanonical kinase cascades regulates glomerular hypertrophy and matrix protein deposition, which are early features of glomerulosclerosis. However, the specific target downstream of the TGFβ receptor involved in the noncanonical signaling is unknown. Here, we show that TGFβ increased the catalytic loop phosphorylation of platelet-derived growth factor receptor β (PDGFRβ), a receptor tyrosine kinase expressed abundantly in glomerular mesangial cells. TGFβ increased phosphorylation of the PI 3-kinase-interacting Tyr-751 residue of PDGFRβ, thus activating Akt. Inhibition of PDGFRβ using a pharmacological inhibitor and siRNAs blocked TGFβ-stimulated phosphorylation of proline-rich Akt substrate of 40 kDa (PRAS40), an intrinsic inhibitory component of mTORC1, and prevented activation of mTORC1 in the absence of any effect on Smad 2/3 phosphorylation. Expression of constitutively active myristoylated Akt reversed the siPDGFRβ-mediated inhibition of mTORC1 activity; however, co-expression of the phospho-deficient mutant of PRAS40 inhibited the effect of myristoylated Akt, suggesting a definitive role of PRAS40 phosphorylation in mTORC1 activation downstream of PDGFRβ in mesangial cells. Additionally, we demonstrate that PDGFRβ-initiated phosphorylation of PRAS40 is required for TGFβ-induced mesangial cell hypertrophy and fibronectin and collagen I (α2) production. Increased activating phosphorylation of PDGFRβ is also associated with enhanced TGFβ expression and mTORC1 activation in the kidney cortex and glomeruli of diabetic mice and rats, respectively. Thus, pursuing TGFβ noncanonical signaling, we identified how TGFβ receptor I achieves mTORC1 activation through PDGFRβ-mediated Akt/PRAS40 phosphorylation to spur mesangial cell hypertrophy and matrix protein accumulation. These findings provide support for targeting PDGFRβ in TGFβ-driven renal fibrosis.
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Affiliation(s)
- Soumya Maity
- Department of Medicine, University of Texas Health Science Center, San Antonio, Texas, USA
| | - Falguni Das
- Department of Medicine, University of Texas Health Science Center, San Antonio, Texas, USA
| | - Balakuntalam S Kasinath
- Department of Medicine, University of Texas Health Science Center, San Antonio, Texas, USA.,Geriatric Research, Education, and Clinical Center, South Texas Veterans Health Care System, San Antonio, Texas, USA
| | | | - Goutam Ghosh Choudhury
- Department of Medicine, University of Texas Health Science Center, San Antonio, Texas, USA .,Department of Veterans Affairs Research, South Texas Veterans Health Care System, San Antonio, Texas, USA.,Geriatric Research, Education, and Clinical Center, South Texas Veterans Health Care System, San Antonio, Texas, USA
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174
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Peroxisome Proliferator-Activated Receptors and Caloric Restriction-Common Pathways Affecting Metabolism, Health, and Longevity. Cells 2020; 9:cells9071708. [PMID: 32708786 PMCID: PMC7407644 DOI: 10.3390/cells9071708] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 07/14/2020] [Accepted: 07/14/2020] [Indexed: 02/06/2023] Open
Abstract
Caloric restriction (CR) is a traditional but scientifically verified approach to promoting health and increasing lifespan. CR exerts its effects through multiple molecular pathways that trigger major metabolic adaptations. It influences key nutrient and energy-sensing pathways including mammalian target of rapamycin, Sirtuin 1, AMP-activated protein kinase, and insulin signaling, ultimately resulting in reductions in basic metabolic rate, inflammation, and oxidative stress, as well as increased autophagy and mitochondrial efficiency. CR shares multiple overlapping pathways with peroxisome proliferator-activated receptors (PPARs), particularly in energy metabolism and inflammation. Consequently, several lines of evidence suggest that PPARs might be indispensable for beneficial outcomes related to CR. In this review, we present the available evidence for the interconnection between CR and PPARs, highlighting their shared pathways and analyzing their interaction. We also discuss the possible contributions of PPARs to the effects of CR on whole organism outcomes.
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175
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Noguchi M, Hirata N, Tanaka T, Suizu F, Nakajima H, Chiorini JA. Autophagy as a modulator of cell death machinery. Cell Death Dis 2020; 11:517. [PMID: 32641772 PMCID: PMC7343815 DOI: 10.1038/s41419-020-2724-5] [Citation(s) in RCA: 121] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 05/08/2020] [Accepted: 05/11/2020] [Indexed: 01/07/2023]
Abstract
The balance between cell death and survival is a critical parameter in the regulation of cells and the maintenance of homeostasis in vivo. Three major mechanisms for cell death have been identified in mammalian cells: apoptosis (type I), autophagic cell death (type II), and necrosis (type III). These three mechanisms have been suggested to engage in cross talk with each other. Among them, autophagy was originally characterized as a cell survival mechanism for amino acid recycling during starvation. Whether autophagy functions primarily in cell survival or cell death is a critical question yet to be answered. Here, we present a comprehensive review of the cell death-related events that take place during autophagy and their underlying mechanisms in cancer and autoimmune disease development.
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Affiliation(s)
- Masayuki Noguchi
- grid.39158.360000 0001 2173 7691Division of Cancer Biology, Institute for Genetic Medicine, Hokkaido University, Sapporo, Japan
| | - Noriyuki Hirata
- grid.39158.360000 0001 2173 7691Division of Cancer Biology, Institute for Genetic Medicine, Hokkaido University, Sapporo, Japan
| | - Tsutomu Tanaka
- grid.94365.3d0000 0001 2297 5165National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD USA
| | - Futoshi Suizu
- grid.39158.360000 0001 2173 7691Division of Cancer Biology, Institute for Genetic Medicine, Hokkaido University, Sapporo, Japan
| | - Hiroshi Nakajima
- grid.136304.30000 0004 0370 1101Department of Allergy and Clinical Immunology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - John A. Chiorini
- grid.94365.3d0000 0001 2297 5165National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD USA
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176
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Demian WL, Persaud A, Jiang C, Coyaud É, Liu S, Kapus A, Kafri R, Raught B, Rotin D. The Ion Transporter NKCC1 Links Cell Volume to Cell Mass Regulation by Suppressing mTORC1. Cell Rep 2020; 27:1886-1896.e6. [PMID: 31067471 DOI: 10.1016/j.celrep.2019.04.034] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 02/13/2019] [Accepted: 04/05/2019] [Indexed: 01/08/2023] Open
Abstract
mTORC1 regulates cellular growth and is activated by growth factors and by essential amino acids such as Leu. Leu enters cells via the Leu transporter LAT1-4F2hc (LAT1). Here we show that the Na+/K+/2Cl- cotransporter NKCC1 (SLC12A2), a known regulator of cell volume, is present in complex with LAT1. We further show that NKCC1 depletion or deletion enhances LAT1 activity, as well as activation of Akt and Erk, leading to activation of mTORC1 in cells, colonic organoids, and mouse colon. Moreover, NKCC1 depletion reduces intracellular Na+ concentration and cell volume (size) and mass and stimulates cell proliferation. NKCC1, therefore, suppresses mTORC1 by inhibiting its key activating signaling pathways. Importantly, by linking ion transport and cell volume regulation to mTORC1 function, NKCC1 provides a long-sought link connecting cell volume (size) to cell mass regulation.
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Affiliation(s)
- Wael L Demian
- Program in Cell Biology, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Biochemistry Department, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Avinash Persaud
- Program in Cell Biology, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Biochemistry Department, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Chong Jiang
- Program in Cell Biology, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Étienne Coyaud
- Princess Margaret Cancer Centre, University Health Network, Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 2C1, Canada
| | - Shixuan Liu
- Biochemistry Department, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Andras Kapus
- Biochemistry Department, University of Toronto, Toronto, ON M5S 1A8, Canada; St. Michael Hospital Research Institute, Toronto, ON M5B 1W8, Canada
| | - Ran Kafri
- Biochemistry Department, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Brian Raught
- Princess Margaret Cancer Centre, University Health Network, Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 2C1, Canada
| | - Daniela Rotin
- Program in Cell Biology, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Biochemistry Department, University of Toronto, Toronto, ON M5S 1A8, Canada.
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177
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Shorning BY, Dass MS, Smalley MJ, Pearson HB. The PI3K-AKT-mTOR Pathway and Prostate Cancer: At the Crossroads of AR, MAPK, and WNT Signaling. Int J Mol Sci 2020; 21:E4507. [PMID: 32630372 PMCID: PMC7350257 DOI: 10.3390/ijms21124507] [Citation(s) in RCA: 314] [Impact Index Per Article: 78.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 06/22/2020] [Accepted: 06/22/2020] [Indexed: 12/13/2022] Open
Abstract
Oncogenic activation of the phosphatidylinositol-3-kinase (PI3K), protein kinase B (PKB/AKT), and mammalian target of rapamycin (mTOR) pathway is a frequent event in prostate cancer that facilitates tumor formation, disease progression and therapeutic resistance. Recent discoveries indicate that the complex crosstalk between the PI3K-AKT-mTOR pathway and multiple interacting cell signaling cascades can further promote prostate cancer progression and influence the sensitivity of prostate cancer cells to PI3K-AKT-mTOR-targeted therapies being explored in the clinic, as well as standard treatment approaches such as androgen-deprivation therapy (ADT). However, the full extent of the PI3K-AKT-mTOR signaling network during prostate tumorigenesis, invasive progression and disease recurrence remains to be determined. In this review, we outline the emerging diversity of the genetic alterations that lead to activated PI3K-AKT-mTOR signaling in prostate cancer, and discuss new mechanistic insights into the interplay between the PI3K-AKT-mTOR pathway and several key interacting oncogenic signaling cascades that can cooperate to facilitate prostate cancer growth and drug-resistance, specifically the androgen receptor (AR), mitogen-activated protein kinase (MAPK), and WNT signaling cascades. Ultimately, deepening our understanding of the broader PI3K-AKT-mTOR signaling network is crucial to aid patient stratification for PI3K-AKT-mTOR pathway-directed therapies, and to discover new therapeutic approaches for prostate cancer that improve patient outcome.
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Affiliation(s)
| | | | | | - Helen B. Pearson
- The European Cancer Stem Cell Research Institute, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff CF24 4HQ, Wales, UK; (B.Y.S.); (M.S.D.); (M.J.S.)
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178
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Hervieu A, Heuss SF, Zhang C, Barrow-McGee R, Joffre C, Ménard L, Clarke PA, Kermorgant S. A PI3K- and GTPase-independent Rac1-mTOR mechanism mediates MET-driven anchorage-independent cell growth but not migration. Sci Signal 2020; 13:eaba8627. [PMID: 32576681 PMCID: PMC7329383 DOI: 10.1126/scisignal.aba8627] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Receptor tyrosine kinases (RTKs) are often overexpressed or mutated in cancers and drive tumor growth and metastasis. In the current model of RTK signaling, including that of MET, downstream phosphatidylinositol 3-kinase (PI3K) mediates both cell proliferation and cell migration, whereas the small guanosine triphosphatase (GTPase) Rac1 mediates cell migration. However, in cultured NIH3T3 and glioblastoma cells, we found that class I PI3K mediated oncogenic MET-induced cell migration but not anchorage-independent growth. In contrast, Rac1 regulated both processes in distinct ways. Downstream of PI3K, Rac1 mediated cell migration through its GTPase activity, whereas independently of PI3K, Rac1 mediated anchorage-independent growth in a GTPase-independent manner through an adaptor function. Through its RKR motif, Rac1 formed a complex with the kinase mTOR to promote its translocation to the plasma membrane, where its activity promoted anchorage-independent growth of the cell cultures. Inhibiting mTOR with rapamycin suppressed the growth of subcutaneous MET-mutant cell grafts in mice, including that of MET inhibitor-resistant cells. These findings reveal a GTPase-independent role for Rac1 in mediating a PI3K-independent MET-to-mTOR pathway and suggest alternative or combined strategies that might overcome resistance to RTK inhibitors in patients with cancer.
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Affiliation(s)
- Alexia Hervieu
- Spatial Signalling Team, Barts Cancer Institute, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ, UK
- Signal Transduction and Molecular Pharmacology Team, CRUK Cancer Therapeutics Unit, Division of Cancer Therapeutics, Institute of Cancer Research, 15 Cotswold Road, Sutton, London SM2 5NG, UK
| | - Sara Farrah Heuss
- Spatial Signalling Team, Barts Cancer Institute, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ, UK
| | - Chi Zhang
- Signal Transduction and Molecular Pharmacology Team, CRUK Cancer Therapeutics Unit, Division of Cancer Therapeutics, Institute of Cancer Research, 15 Cotswold Road, Sutton, London SM2 5NG, UK
| | - Rachel Barrow-McGee
- Spatial Signalling Team, Barts Cancer Institute, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ, UK
| | - Carine Joffre
- Spatial Signalling Team, Barts Cancer Institute, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ, UK
| | - Ludovic Ménard
- Spatial Signalling Team, Barts Cancer Institute, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ, UK
| | - Paul Andrew Clarke
- Signal Transduction and Molecular Pharmacology Team, CRUK Cancer Therapeutics Unit, Division of Cancer Therapeutics, Institute of Cancer Research, 15 Cotswold Road, Sutton, London SM2 5NG, UK
| | - Stéphanie Kermorgant
- Spatial Signalling Team, Barts Cancer Institute, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ, UK.
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179
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Shang C, Zhou H, Liu W, Shen T, Luo Y, Huang S. Iron chelation inhibits mTORC1 signaling involving activation of AMPK and REDD1/Bnip3 pathways. Oncogene 2020; 39:5201-5213. [PMID: 32541839 PMCID: PMC7366895 DOI: 10.1038/s41388-020-1366-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 06/02/2020] [Accepted: 06/08/2020] [Indexed: 12/15/2022]
Abstract
The mammalian target of rapamycin (mTOR) functions as two complexes (mTORC1 and mTORC2), regulating cell growth and metabolism. Aberrant mTOR signaling occurs frequently in cancers, so mTOR has become an attractive target for cancer therapy. Iron chelators have emerged as promising anticancer agents. However, the mechanisms underlying the anticancer action of iron chelation are not fully understood. Particularly, reports on the effects of iron chelation on mTOR complexes are inconsistent or controversial. Here, we found that iron chelators consistently inhibited mTORC1 signaling, which was blocked by pretreatment with ferrous sulfate. Mechanistically, iron chelation-induced mTORC1 inhibition was not related to ROS induction, copper chelation, or PP2A activation. Instead, activation of AMPK pathway mainly and activation of both HIF-1/REDD1 and Bnip3 pathways partially contribute to iron chelation-induced mTORC1 inhibition. Our findings indicate that iron chelation inhibits mTORC1 via multiple pathways and iron is essential for mTORC1 activation.
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Affiliation(s)
- Chaowei Shang
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, LA, 71130-3932, USA.,Feist-Weiller Cancer Center, Louisiana State University Health Sciences Center, Shreveport, LA, 71130-3932, USA
| | - Hongyu Zhou
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, LA, 71130-3932, USA
| | - Wang Liu
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, LA, 71130-3932, USA
| | - Tao Shen
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, LA, 71130-3932, USA.,Feist-Weiller Cancer Center, Louisiana State University Health Sciences Center, Shreveport, LA, 71130-3932, USA
| | - Yan Luo
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, LA, 71130-3932, USA
| | - Shile Huang
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, LA, 71130-3932, USA. .,Feist-Weiller Cancer Center, Louisiana State University Health Sciences Center, Shreveport, LA, 71130-3932, USA.
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180
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Drizyte-Miller K, Chen J, Cao H, Schott MB, McNiven MA. The small GTPase Rab32 resides on lysosomes to regulate mTORC1 signaling. J Cell Sci 2020; 133:jcs236661. [PMID: 32295849 PMCID: PMC7295596 DOI: 10.1242/jcs.236661] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 04/01/2020] [Indexed: 12/24/2022] Open
Abstract
Epithelial cells, such as liver-resident hepatocytes, rely heavily on the Rab family of small GTPases to perform membrane trafficking events that dictate cell physiology and metabolism. Not surprisingly, disruption of several Rab proteins can manifest in metabolic diseases or cancer. Rab32 is expressed in many secretory epithelial cells but its role in cellular metabolism is virtually unknown. In this study, we find that Rab32 associates with lysosomes and regulates proliferation and cell size of Hep3B hepatoma and HeLa cells. Specifically, we identify that Rab32 supports the mechanistic target of rapamycin complex 1 (mTORC1) signaling under basal and amino acid-stimulated conditions. Consistent with inhibited mTORC1, an increase in nuclear TFEB localization and lysosome biogenesis is also observed in Rab32-depleted cells. Finally, we find that Rab32 interacts with mTOR kinase, and that loss of Rab32 reduces the association of mTOR and mTORC1 pathway proteins with lysosomes, suggesting that Rab32 regulates lysosomal mTOR trafficking. In summary, these findings suggest that Rab32 functions as a novel regulator of cellular metabolism through supporting mTORC1 signaling.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Kristina Drizyte-Miller
- Biochemistry and Molecular Biology Program, Mayo Clinic Graduate School of Biomedical Sciences, Mayo Clinic, 200 1st Street SW, Rochester, MN 55905, USA
| | - Jing Chen
- Center for Basic Research in Digestive Diseases, Division of Gastroenterology and Hepatology, Mayo Clinic, 200 1st Street SW, Rochester, MN 55905, USA
| | - Hong Cao
- Center for Basic Research in Digestive Diseases, Division of Gastroenterology and Hepatology, Mayo Clinic, 200 1st Street SW, Rochester, MN 55905, USA
| | - Micah B Schott
- Center for Basic Research in Digestive Diseases, Division of Gastroenterology and Hepatology, Mayo Clinic, 200 1st Street SW, Rochester, MN 55905, USA
| | - Mark A McNiven
- Biochemistry and Molecular Biology Program, Mayo Clinic Graduate School of Biomedical Sciences, Mayo Clinic, 200 1st Street SW, Rochester, MN 55905, USA
- Center for Basic Research in Digestive Diseases, Division of Gastroenterology and Hepatology, Mayo Clinic, 200 1st Street SW, Rochester, MN 55905, USA
- Department of Biochemistry and Molecular Biology, Mayo Clinic, 200 1st Street SW, Rochester, MN 55905, USA
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181
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Hansmann P, Brückner A, Kiontke S, Berkenfeld B, Seebohm G, Brouillard P, Vikkula M, Jansen FE, Nellist M, Oeckinghaus A, Kümmel D. Structure of the TSC2 GAP Domain: Mechanistic Insight into Catalysis and Pathogenic Mutations. Structure 2020; 28:933-942.e4. [PMID: 32502382 DOI: 10.1016/j.str.2020.05.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 02/06/2020] [Accepted: 05/15/2020] [Indexed: 12/17/2022]
Abstract
The TSC complex is the cognate GTPase-activating protein (GAP) for the small GTPase Rheb and a crucial regulator of the mechanistic target of rapamycin complex 1 (mTORC1). Mutations in the TSC1 and TSC2 subunits of the complex cause tuberous sclerosis complex (TSC). We present the crystal structure of the catalytic asparagine-thumb GAP domain of TSC2. A model of the TSC2-Rheb complex and molecular dynamics simulations suggest that TSC2 Asn1643 and Rheb Tyr35 are key active site residues, while Rheb Arg15 and Asp65, previously proposed as catalytic residues, contribute to the TSC2-Rheb interface and indirectly aid catalysis. The TSC2 GAP domain is further stabilized by interactions with other TSC2 domains. We characterize TSC2 variants that partially affect TSC2 functionality and are associated with atypical symptoms in patients, suggesting that mutations in TSC1 and TSC2 might predispose to neurological and vascular disorders without fulfilling the clinical criteria for TSC.
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Affiliation(s)
- Patrick Hansmann
- Westfälische Wilhelms-Universität, Institute of Biochemistry, Wilhelm Klemm-Str. 2, 48149 Münster, Germany
| | - Anne Brückner
- Westfälische Wilhelms-Universität, Institute of Biochemistry, Wilhelm Klemm-Str. 2, 48149 Münster, Germany; Westfälische Wilhelms-Universität, Institute of Molecular Tumor Biology, Robert-Koch-Str. 43, 48149 Münster, Germany
| | - Stephan Kiontke
- Philipps-Universität Marburg, Faculty of Biology, Department of Plant Physiology and Photobiology, Karl-von-Frisch-Str. 8, 35032 Marburg, Germany
| | - Bianca Berkenfeld
- Westfälische Wilhelms-Universität, Institute of Biochemistry, Wilhelm Klemm-Str. 2, 48149 Münster, Germany
| | - Guiscard Seebohm
- University Hospital Münster, Institute for Genetics of Heart Diseases, Department of Cardiovascular Medicine, Robert-Koch-Str. 45, 48149 Münster, Germany
| | - Pascal Brouillard
- Université Catholique de Louvain, de Duve Institute, Human Molecular Genetics, Brussels, Belgium
| | - Miikka Vikkula
- Université Catholique de Louvain, de Duve Institute, Human Molecular Genetics, Brussels, Belgium; WELBIO (Walloon Excellence in Lifesciences and Biotechnology), de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
| | - Floor E Jansen
- Department of Child Neurology, Brain Center UMC Utrecht, Utrecht, the Netherlands
| | - Mark Nellist
- Department of Clinical Genetics, Erasmus Medical Center, Wytemaweg 80, 3015 CN Rotterdam, the Netherlands
| | - Andrea Oeckinghaus
- Westfälische Wilhelms-Universität, Institute of Molecular Tumor Biology, Robert-Koch-Str. 43, 48149 Münster, Germany
| | - Daniel Kümmel
- Westfälische Wilhelms-Universität, Institute of Biochemistry, Wilhelm Klemm-Str. 2, 48149 Münster, Germany.
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182
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Jeong YJ, Hwang SK, Magae J, Chang YC. Ascofuranone suppresses invasion and F-actin cytoskeleton organization in cancer cells by inhibiting the mTOR complex 1 signaling pathway. Cell Oncol (Dordr) 2020; 43:793-805. [PMID: 32488849 DOI: 10.1007/s13402-020-00520-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 03/29/2020] [Accepted: 04/15/2020] [Indexed: 11/28/2022] Open
Abstract
PURPOSE Ascofuranone is an antiviral antibiotic that is known to exert multiple anti-tumor effects, including cell cycle arrest, inhibition of mitochondrial respiration, and inhibition of angiogenesis. In this study, we investigated the molecular mechanisms underlying the anti-metastatic effects of ascofuranone in insulin-like growth factor-I (IGF-1)-responsive cancer cells. METHODS The inhibitory effect of ascofuranone on cancer cell migration and invasion was assessed using scratch wound healing and Matrigel invasion assays, respectively. F-actin cytoskeleton organization was assessed using FITC conjugated phalloidin staining. Target gene expression was evaluated using Western blotting and gene silencing was performed using siRNA transfections. Finally, the anti-metastatic effect of ascofuranone was investigated in vivo. RESULTS We found that ascofuranone suppressed IGF-1-induced cell migration, invasion and motility in multiple cancer cell lines. The effects of ascofuranone on actin cytoskeleton organization were found to be mediated by suppression of the mTOR/p70S6K/4EBP1 pathway. Ascofuranone inhibited IGF-1-induced mTOR phosphorylation and actin cytoskeleton organization via upregulation of AMPK and downregulation of Akt phosphorylation. It also selectively suppressed the IGF-1-induced mTOR complex (mTORC)1 by phosphorylation of Raptor, but did not affect mTORC2. Furthermore, we found that focal adhesion kinase (FAK) activation decreased in response to ascofuranone, rapamycin, compound C and wortmannin treatment. Finally, we found that ascofuranone suppressed phosphorylation of FAK and mTOR and dephosphorylation of Raptor in cancerous metastatic lung tissues in vivo. CONCLUSIONS Our data indicate that ascofuranone suppresses IGF-1-induced cancer cell migration and invasion by blocking actin cytoskeleton organization and FAK activation through inhibition of the mTORC1 pathway, and reveal a novel anti-metastatic function of this compound.
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Affiliation(s)
- Yun-Jeong Jeong
- Research Institute of Biomedical Engineering, Department of Medicine, Catholic University of Daegu School of Medicine, 42472, Deagu, Korea
| | - Soon-Kyung Hwang
- Research Institute of Biomedical Engineering, Department of Medicine, Catholic University of Daegu School of Medicine, 42472, Deagu, Korea
| | - Junji Magae
- Magae Bioscience Institute, 49-4 Fujimidai, 300-1263, Tsukuba, Japan
| | - Young-Chae Chang
- Research Institute of Biomedical Engineering, Department of Medicine, Catholic University of Daegu School of Medicine, 42472, Deagu, Korea. .,Department of Cell Biology, Catholic University of Daegu School of Medicine, 3056-6, Daemyung-4-Dong, Nam-gu, 42472, Daegu, Korea.
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183
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Abstract
A complex molecular machinery converges on the surface of lysosomes to ensure that the growth-promoting signaling mediated by mechanistic target of rapamycin complex 1 (mTORC1) is tightly controlled by the availability of nutrients and growth factors. The final step in this activation process is dependent on Rheb, a small GTPase that binds to mTOR and allosterically activates its kinase activity. Here we review the mechanisms that determine the subcellular localization of Rheb (and the closely related RhebL1 protein) as well as the significance of these mechanisms for controlling mTORC1 activation. In particular, we explore how the relatively weak membrane interactions conferred by C-terminal farnesylation are critical for the ability of Rheb to activate mTORC1. In addition to supporting transient membrane interactions, Rheb C-terminal farnesylation also supports an interaction between Rheb and the δ subunit of phosphodiesterase 6 (PDEδ). This interaction provides a potential mechanism for targeting Rheb to membranes that contain Arl2, a small GTPase that triggers the release of prenylated proteins from PDEδ. The minimal membrane targeting conferred by C-terminal farnesylation of Rheb and RhebL1 distinguishes them from other members of the Ras superfamily that possess additional membrane interaction motifs that work with farnesylation for enrichment on the specific subcellular membranes where they engage key effectors. Finally, we highlight diversity in Rheb membrane targeting mechanisms as well as the potential for alternative mTORC1 activation mechanisms across species.
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Affiliation(s)
- Brittany Angarola
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, 06510, USA.,Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Shawn M Ferguson
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, 06510, USA.,Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale University School of Medicine, New Haven, CT, 06510, USA
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184
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Andò S, Naimo GD, Gelsomino L, Catalano S, Mauro L. Novel insights into adiponectin action in breast cancer: Evidence of its mechanistic effects mediated by ERα expression. Obes Rev 2020; 21:e13004. [PMID: 32067339 DOI: 10.1111/obr.13004] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 01/10/2020] [Indexed: 12/11/2022]
Abstract
This review describes the multifaceted effects of adiponectin on breast cancer cell signalling, tumour metabolism, and microenvironment. It is largely documented that low adiponectin levels are associated with an increased risk of breast cancer. However, it needs to be still clarified what are the extents of the decrease of local/intra-tumoural adiponectin concentrations, which promote breast tumour malignancy. Most of the anti-proliferative and pro-apoptotic effects induced by adiponectin have been obtained in breast cancer cells not expressing estrogen receptor alpha (ERα). Here, we will highlight recent findings demonstrating the mechanistic effects through which adiponectin is able to fuel genomic and non-genomic estrogen signalling, inhibiting LKB1/AMPK/mTOR/S6K pathway and switching energy balance. Therefore, it emerges that the reduced adiponectin levels in patients with obesity work to sustain tumour growth and progression in ERα-positive breast cancer cells. All this may contribute to remove the misleading paradigm that adiponectin univocally inhibits breast cancer cell growth and progression independently on ERα status. The latter concept, here clearly provided by pre-clinical studies, may have translational relevance adopting adiponectin as a potential therapeutic tool. Indeed, the interfering role of ERα on adiponectin action addresses how a separate assessment of adiponectin treatment needs to be considered in novel therapeutic strategies for ERα-positive and ERα-negative breast cancer.
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Affiliation(s)
- Sebastiano Andò
- Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Arcavacata di Rende, Italy.,Centro Sanitario, University of Calabria, Arcavacata di Rende, Italy
| | - Giuseppina Daniela Naimo
- Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Arcavacata di Rende, Italy
| | - Luca Gelsomino
- Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Arcavacata di Rende, Italy
| | - Stefania Catalano
- Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Arcavacata di Rende, Italy
| | - Loredana Mauro
- Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Arcavacata di Rende, Italy
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185
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Deregulated PTEN/PI3K/AKT/mTOR signaling in prostate cancer: Still a potential druggable target? BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1867:118731. [PMID: 32360668 DOI: 10.1016/j.bbamcr.2020.118731] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 04/21/2020] [Accepted: 04/23/2020] [Indexed: 01/13/2023]
Abstract
Although the prognosis of patients with localized prostate cancer is good after surgery, with a favorable response to androgen deprivation therapy, about one third of them invariably relapse, and progress to castration-resistant prostate cancer. Overall, prostate cancer therapies remain scarcely effective, thus it is mandatory to devise alternative treatments enhancing the efficacy of surgical castration and hormone administration. Dysregulation of the phosphoinositide 3-kinase pathway has attracted growing attention in prostate cancer due to the highly frequent association of epigenetic and post-translational modifications as well as to genetic alterations of both phosphoinositide 3-kinase and PTEN to onset and/or progression of this malignancy, and to resistance to canonical androgen-deprivation therapy. Here we provide a summary of the biological functions of the major players of this cascade and their deregulation in prostate cancer, summarizing the results of preclinical and clinical studies with PI3K signaling inhibitors and the reasons of failure independent from genomic changes.
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186
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Prossomariti A, Piazzi G, Alquati C, Ricciardiello L. Are Wnt/β-Catenin and PI3K/AKT/mTORC1 Distinct Pathways in Colorectal Cancer? Cell Mol Gastroenterol Hepatol 2020; 10:491-506. [PMID: 32334125 PMCID: PMC7369353 DOI: 10.1016/j.jcmgh.2020.04.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 04/05/2020] [Accepted: 04/09/2020] [Indexed: 02/07/2023]
Abstract
Wnt/β-catenin and phosphatidylinositol-3-kinase/protein kinase B/mammalian target of rapamycin complex 1 (PI3K/AKT/mTORC1) pathways both are critically involved in colorectal cancer (CRC) development, although they are implicated in the modulation of distinct oncogenic mechanisms. In homeostatic and pathologic conditions, these pathways show a fine regulation based mainly on feedback mechanisms, and are connected at multiple levels involving both upstream and downstream common effectors. The ability of the Wnt/β-catenin and PI3K/AKT/mTORC1 pathways to reciprocally control themselves represents one of the main resistance mechanisms to selective inhibitors in CRC, leading to the hypothesis that in specific settings, particularly in cancer driven by genetic alterations in Wnt/β-catenin signaling, the relationship between Wnt/β-catenin and PI3K/AKT/mTORC1 pathways could be so close that they should be considered as a unique therapeutic target. This review provides an update on the Wnt/β-catenin and PI3K/AKT/mTORC1 pathway interconnections in CRC, describing the main molecular players and the potential implications of combined inhibitors as an approach for CRC chemoprevention and treatment.
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Affiliation(s)
- Anna Prossomariti
- Department of Medical and Surgical Sciences, University of Bologna, Bologna, Italy,Center for Applied Biomedical Research, S. Orsola Hospital, University of Bologna, Bologna, Italy,Anna Prossomariti, PhD, Center for Applied Biomedical Research, S. Orsola Hospital, Via Massarenti 9, 40138, Bologna, Italy. fax: (39) 051-2143902.
| | - Giulia Piazzi
- Department of Medical and Surgical Sciences, University of Bologna, Bologna, Italy,Center for Applied Biomedical Research, S. Orsola Hospital, University of Bologna, Bologna, Italy
| | - Chiara Alquati
- Department of Medical and Surgical Sciences, University of Bologna, Bologna, Italy,Center for Applied Biomedical Research, S. Orsola Hospital, University of Bologna, Bologna, Italy
| | - Luigi Ricciardiello
- Department of Medical and Surgical Sciences, University of Bologna, Bologna, Italy,Center for Applied Biomedical Research, S. Orsola Hospital, University of Bologna, Bologna, Italy,Correspondence Address correspondence to: Luigi Ricciardiello, MD, Department of Medical and Surgical Sciences, Via Massarenti 9, 40138, Bologna, Italy. fax: (39) 051-2143381
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187
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Liu GY, Sabatini DM. mTOR at the nexus of nutrition, growth, ageing and disease. Nat Rev Mol Cell Biol 2020; 21:183-203. [PMID: 31937935 PMCID: PMC7102936 DOI: 10.1038/s41580-019-0199-y] [Citation(s) in RCA: 1419] [Impact Index Per Article: 354.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/26/2019] [Indexed: 12/21/2022]
Abstract
The mTOR pathway integrates a diverse set of environmental cues, such as growth factor signals and nutritional status, to direct eukaryotic cell growth. Over the past two and a half decades, mapping of the mTOR signalling landscape has revealed that mTOR controls biomass accumulation and metabolism by modulating key cellular processes, including protein synthesis and autophagy. Given the pathway's central role in maintaining cellular and physiological homeostasis, dysregulation of mTOR signalling has been implicated in metabolic disorders, neurodegeneration, cancer and ageing. In this Review, we highlight recent advances in our understanding of the complex regulation of the mTOR pathway and discuss its function in the context of physiology, human disease and pharmacological intervention.
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Affiliation(s)
- Grace Y Liu
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
- Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA, USA
- Broad Institute, Cambridge, MA, USA
- The David H. Koch Institute for Integrative Cancer Research at MIT, Cambridge, MA, USA
| | - David M Sabatini
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA.
- Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Broad Institute, Cambridge, MA, USA.
- The David H. Koch Institute for Integrative Cancer Research at MIT, Cambridge, MA, USA.
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188
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Cell Death Pathways in Ischemic Stroke and Targeted Pharmacotherapy. Transl Stroke Res 2020; 11:1185-1202. [PMID: 32219729 DOI: 10.1007/s12975-020-00806-z] [Citation(s) in RCA: 177] [Impact Index Per Article: 44.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Revised: 03/04/2020] [Accepted: 03/10/2020] [Indexed: 02/07/2023]
Abstract
Ischemic stroke is one of the significant causes of morbidity and mortality, affecting millions of people across the globe. Cell injury in the infarct region is an inevitable consequence of focal cerebral ischemia. Subsequent reperfusion exacerbates the harmful effect and increases the infarct volume. These cellular injuries follow either a regulated pathway involving tightly structured signaling cascades and molecularly defined effector mechanisms or a non-regulated pathway, also known as accidental cell death, where the process is biologically uncontrolled. Classical cell death pathways are long established and well reported in several articles that majorly define apoptotic cell death. A recent focus on cell death study also considers investigation on non-classical pathways that are tightly regulated, may or may not involve caspases, but non-apoptotic. Pathological cell death is a cardinal feature of different neurodegenerative diseases. Although ischemia cannot be classified as a neurodegenerative disease, it is a cerebrovascular event where the infarct region exhibits aberrant cell death. Over the past few decades, several therapeutic options have been implicated for ischemic stroke. However, their use has been hampered owing to the number of limitations that they possess. Ischemic penumbral neurons undergo apoptosis and become dysfunctional; however, they are salvageable. Thus, understanding the role of different cell death pathways is crucial to aid in the modern treatment of protecting apoptotic neurons.
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189
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Akimoto R, Tanaka T, Nakano T, Hozumi Y, Kawamae K, Goto K. DGKζ depletion attenuates HIF-1α induction and SIRT1 expression, but enhances TAK1-mediated AMPKα phosphorylation under hypoxia. Cell Signal 2020; 71:109618. [PMID: 32224048 DOI: 10.1016/j.cellsig.2020.109618] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 03/21/2020] [Accepted: 03/25/2020] [Indexed: 12/31/2022]
Abstract
Cells cope with environmental changes through various mechanisms. Pathways involving HIF-1, SIRT1, and AMPK play major roles in energy homeostasis under stress conditions. Diacylglycerol kinase (DGK) constitutes an enzyme family that catalyzes conversion of diacylglycerol to phosphatidic acid. We reported earlier that energy depletion such as ischemia induces proteasomal degradation of DGKζ before cell death, suggesting involvement of DGKζ in energy homeostasis. This study examines how DGKζ depletion affects the regulation of HIF-1α, SIRT1, and AMPKα. Under hypoxia DGKζ depletion attenuates HIF-1α induction and SIRT1 expression, which might render cells vulnerable to energy stress. However, DGKζ depletion engenders enhanced AMPKα phosphorylation by upstream kinase TAK1 and an increase in intracellular ATP levels. Results suggest that DGKζ exerts a suppressive effect on TAK1 activity in the AMPK activation mechanism, and that DGKζ depletion might engender dysregulation of the AMPK-mediated energy sensor system.
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Affiliation(s)
- Ryo Akimoto
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata 990-9585, Japan; Department of Anesthesiology, Yamagata University School of Medicine, Yamagata 990-9585, Japan
| | - Toshiaki Tanaka
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata 990-9585, Japan.
| | - Tomoyuki Nakano
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata 990-9585, Japan
| | - Yasukazu Hozumi
- Department of Cell Biology and Morphology, Akita University Graduate School of Medicine, Akita 010-8543, Japan
| | - Kaneyuki Kawamae
- Department of Anesthesiology, Yamagata University School of Medicine, Yamagata 990-9585, Japan
| | - Kaoru Goto
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata 990-9585, Japan.
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190
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Saravia J, Raynor JL, Chapman NM, Lim SA, Chi H. Signaling networks in immunometabolism. Cell Res 2020; 30:328-342. [PMID: 32203134 PMCID: PMC7118125 DOI: 10.1038/s41422-020-0301-1] [Citation(s) in RCA: 117] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Accepted: 02/24/2020] [Indexed: 02/06/2023] Open
Abstract
Adaptive immunity is essential for pathogen and tumor eradication, but may also trigger uncontrolled or pathological inflammation. T cell receptor, co-stimulatory and cytokine signals coordinately dictate specific signaling networks that trigger the activation and functional programming of T cells. In addition, cellular metabolism promotes T cell responses and is dynamically regulated through the interplay of serine/threonine kinases, immunological cues and nutrient signaling networks. In this review, we summarize the upstream regulators and signaling effectors of key serine/threonine kinase-mediated signaling networks, including PI3K–AGC kinases, mTOR and LKB1–AMPK pathways that regulate metabolism, especially in T cells. We also provide our perspectives about the pending questions and clinical applicability of immunometabolic signaling. Understanding the regulators and effectors of immunometabolic signaling networks may uncover therapeutic targets to modulate metabolic programming and T cell responses in human disease.
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Affiliation(s)
- Jordy Saravia
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Jana L Raynor
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Nicole M Chapman
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Seon Ah Lim
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Hongbo Chi
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA.
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191
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Abstract
Cellular metabolism is at the foundation of all biological activities. The catabolic processes that support cellular bioenergetics and survival have been well studied. By contrast, how cells alter their metabolism to support anabolic biomass accumulation is less well understood. During the commitment to cell proliferation, extensive metabolic rewiring must occur in order for cells to acquire sufficient nutrients such as glucose, amino acids, lipids and nucleotides, which are necessary to support cell growth and to deal with the redox challenges that arise from the increased metabolic activity associated with anabolic processes. Defining the mechanisms of this metabolic adaptation for cell growth and proliferation is now a major focus of research. Understanding the principles that guide anabolic metabolism may ultimately enhance ways to treat diseases that involve deregulated cell growth and proliferation, such as cancer.
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192
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Ferrara-Romeo I, Martinez P, Saraswati S, Whittemore K, Graña-Castro O, Thelma Poluha L, Serrano R, Hernandez-Encinas E, Blanco-Aparicio C, Maria Flores J, Blasco MA. The mTOR pathway is necessary for survival of mice with short telomeres. Nat Commun 2020; 11:1168. [PMID: 32127537 PMCID: PMC7054554 DOI: 10.1038/s41467-020-14962-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 01/31/2020] [Indexed: 12/24/2022] Open
Abstract
Telomerase deficiency leads to age-related diseases and shorter lifespans. Inhibition of the mechanistic target of rapamycin (mTOR) delays aging and age-related pathologies. Here, we show that telomerase deficient mice with short telomeres (G2-Terc−/−) have an hyper-activated mTOR pathway with increased levels of phosphorylated ribosomal S6 protein in liver, skeletal muscle and heart, a target of mTORC1. Transcriptional profiling confirms mTOR activation in G2-Terc−/− livers. Treatment of G2-Terc−/− mice with rapamycin, an inhibitor of mTORC1, decreases survival, in contrast to lifespan extension in wild-type controls. Deletion of mTORC1 downstream S6 kinase 1 in G3-Terc−/− mice also decreases longevity, in contrast to lifespan extension in single S6K1−/− female mice. These findings demonstrate that mTOR is important for survival in the context of short telomeres, and that its inhibition is deleterious in this setting. These results are of clinical interest in the case of human syndromes characterized by critically short telomeres. Telomerase deficiency leads to age-related diseases and shortened lifespan, while inhibition of the mTOR pathway delays aging. Here, the authors show that inhibition of mTORC1 signaling shortens the lifespan of telomerase deficient mice.
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Affiliation(s)
- Iole Ferrara-Romeo
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Centre (CNIO), Melchor Fernández Almagro 3, E-28029, Madrid, Spain
| | - Paula Martinez
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Centre (CNIO), Melchor Fernández Almagro 3, E-28029, Madrid, Spain
| | - Sarita Saraswati
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Centre (CNIO), Melchor Fernández Almagro 3, E-28029, Madrid, Spain
| | - Kurt Whittemore
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Centre (CNIO), Melchor Fernández Almagro 3, E-28029, Madrid, Spain
| | - Osvaldo Graña-Castro
- Bioinformatics Unit, Structural Biology and Biocomputing Program, Spanish National Cancer Centre (CNIO), Melchor Fernández Almagro 3, E-28029, Madrid, Spain
| | - Lydia Thelma Poluha
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Centre (CNIO), Melchor Fernández Almagro 3, E-28029, Madrid, Spain
| | - Rosa Serrano
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Centre (CNIO), Melchor Fernández Almagro 3, E-28029, Madrid, Spain
| | - Elena Hernandez-Encinas
- Experimental Therapeutics Program, Spanish National Cancer Centre (CNIO), Melchor Fernández Almagro 3, E-28029, Madrid, Spain
| | - Carmen Blanco-Aparicio
- Experimental Therapeutics Program, Spanish National Cancer Centre (CNIO), Melchor Fernández Almagro 3, E-28029, Madrid, Spain
| | - Juana Maria Flores
- Animal Surgery and Medicine Department, Faculty of Veterinary Science, Complutense University of Madrid, Avenida Puerta de Hierro s/n, E-28040, Madrid, Spain
| | - Maria A Blasco
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Centre (CNIO), Melchor Fernández Almagro 3, E-28029, Madrid, Spain.
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193
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Inoue T, Kokubo T, Daino K, Yanagihara H, Watanabe F, Tsuruoka C, Amasaki Y, Morioka T, Homma‐Takeda S, Kobayashi T, Hino O, Shimada Y, Kakinuma S. Interstitial chromosomal deletion of the tuberous sclerosis complex 2 locus is a signature for radiation-associated renal tumors in Eker rats. Cancer Sci 2020; 111:840-848. [PMID: 31925975 PMCID: PMC7060461 DOI: 10.1111/cas.14307] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 12/23/2019] [Accepted: 12/31/2019] [Indexed: 01/01/2023] Open
Abstract
Ionizing radiation can damage DNA and, therefore, is a risk factor for cancer. Eker rats, which carry a heterozygous germline mutation in the tumor-suppressor gene tuberous sclerosis complex 2 (Tsc2), are susceptible to radiation-induced renal carcinogenesis. However, the molecular mechanisms involved in Tsc2 inactivation are unclear. We subjected Fischer 344 × Eker (Long Evans Tsc2+/- ) F1 hybrid rats to gamma-irradiation (2 Gy) at gestational day 19 (GD19) or postnatal day 5 (PND5) and investigated the patterns of genomic alterations in the Tsc2 allele of renal tumors that developed at 1 year after irradiation (N = 24 tumors for GD19, N = 10 for PND5), in comparison with spontaneously developed tumors (N = 8 tumors). Gamma-irradiation significantly increased the multiplicity of renal tumors. The frequency of LOH at the chromosome 10q12 region, including the Tsc2 locus, was 38%, 29% and 60% in renal carcinomas developed from the nonirradiated, GD19 and PND5 groups, respectively. Array comparative genomic hybridization analysis revealed that the LOH patterns on chromosome 10 in renal carcinomas were classified into chromosomal missegregation, mitotic recombination and chromosomal deletion types. LOH of the interstitial chromosomal deletion type was observed only in radiation-associated carcinomas. Sequence analysis for the wild-type Tsc2 allele in the LOH-negative carcinomas identified deletions (nonirradiated: 26%; GD19: 21%) and base-substitution mutations (GD19: 4%). Reduced expression of Tsc2 was also observed in the majority of the LOH-negative carcinomas. Our results suggest that interstitial chromosomal deletion is a characteristic mutagenic event caused by ionizing radiation, and it may contribute to the assessment of radiation-induced cancer risk.
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Affiliation(s)
- Tatsuya Inoue
- Department of Radiation Effects ResearchNational Institute of Radiological SciencesNational Institutes for Quantum and Radiological Science and TechnologyChibaJapan
- Department of RadiologyJuntendo University Urayasu HospitalChibaJapan
| | - Toshiaki Kokubo
- Laboratory Animal and Genome Sciences SectionNational Institute of Radiological SciencesNational Institutes for Quantum and Radiological Science and TechnologyChibaJapan
| | - Kazuhiro Daino
- Department of Radiation Effects ResearchNational Institute of Radiological SciencesNational Institutes for Quantum and Radiological Science and TechnologyChibaJapan
| | - Hiromi Yanagihara
- Department of Radiation Effects ResearchNational Institute of Radiological SciencesNational Institutes for Quantum and Radiological Science and TechnologyChibaJapan
| | - Fumiko Watanabe
- Department of Radiation Effects ResearchNational Institute of Radiological SciencesNational Institutes for Quantum and Radiological Science and TechnologyChibaJapan
| | - Chizuru Tsuruoka
- Department of Radiation Effects ResearchNational Institute of Radiological SciencesNational Institutes for Quantum and Radiological Science and TechnologyChibaJapan
| | - Yoshiko Amasaki
- Department of Radiation Effects ResearchNational Institute of Radiological SciencesNational Institutes for Quantum and Radiological Science and TechnologyChibaJapan
| | - Takamitsu Morioka
- Department of Radiation Effects ResearchNational Institute of Radiological SciencesNational Institutes for Quantum and Radiological Science and TechnologyChibaJapan
| | - Shino Homma‐Takeda
- Department of Basic Medical Sciences for Radiation DamagesNational Institute of Radiological SciencesNational Institutes for Quantum and Radiological Science and TechnologyChibaJapan
| | - Toshiyuki Kobayashi
- Department of Pathology and OncologyFaculty of MedicineJuntendo UniversityTokyoJapan
| | - Okio Hino
- Department of Pathology and OncologyFaculty of MedicineJuntendo UniversityTokyoJapan
| | - Yoshiya Shimada
- National Institutes for Quantum and Radiological Science and TechnologyChibaJapan
- Present address:
Institute for Environmental SciencesAomoriJapan
| | - Shizuko Kakinuma
- Department of Radiation Effects ResearchNational Institute of Radiological SciencesNational Institutes for Quantum and Radiological Science and TechnologyChibaJapan
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194
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Liu W, Stachura P, Xu HC, Umesh Ganesh N, Cox F, Wang R, Lang KS, Gopalakrishnan J, Häussinger D, Homey B, Lang PA, Pandyra AA. Repurposing the serotonin agonist Tegaserod as an anticancer agent in melanoma: molecular mechanisms and clinical implications. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2020; 39:38. [PMID: 32085796 PMCID: PMC7035645 DOI: 10.1186/s13046-020-1539-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 02/05/2020] [Indexed: 11/10/2022]
Abstract
BACKGROUND New therapies are urgently needed in melanoma particularly in late-stage patients not responsive to immunotherapies and kinase inhibitors. METHODS Drug screening, IC50 determinations as well as synergy assays were detected by the MTT assay. Apoptosis using Annexin V and 7AAD staining was assessed using flow cytometry. TUNEL staining was performed using immunocytochemistry. Changes in phosphorylation of key molecules in PI3K/Akt/mTOR and other relevant pathways were detected by western blot as well as immunocytochemistry. To assess in vivo anti-tumor activity of Tegaserod, syngeneic intravenous and subcutaneous melanoma xenografts were used. Immunocytochemical staining was performed to detect expression of active Caspase-3, cleaved Caspase 8 and p-S6 in tumors. Evaluation of immune infiltrates was carried out by flow cytometry. RESULTS Using a screen of 770 pharmacologically active and/or FDA approved drugs, we identified Tegaserod (Zelnorm, Zelmac) as a compound with novel anti-cancer activity which induced apoptosis in murine and human malignant melanoma cell lines. Tegaserod (TM) is a serotonin receptor 4 agonist (HTR4) used in the treatment of irritable bowel syndrome (IBS). TM's anti-melanoma apoptosis-inducing effects were uncoupled from serotonin signaling and attributed to PI3K/Akt/mTOR signaling inhibition. Specifically, TM blunted S6 phosphorylation in both BRAFV600E and BRAF wildtype (WT) melanoma cell lines. TM decreased tumor growth and metastases as well as increased survival in an in vivo syngeneic immune-competent model. In vivo, TM also caused tumor cell apoptosis, blunted PI3K/Akt/mTOR signaling and decreased S6 phosphorylation. Furthermore TM decreased the infiltration of immune suppressive regulatory CD4+CD25+ T cells and FOXP3 and ROR-γt positive CD4+ T cells. Importantly, TM synergized with Vemurafenib, the standard of care drug used in patients with late stage disease harboring the BRAFV600E mutation and could be additively or synergistically combined with Cobimetinib in both BRAFV600E and BRAF WT melanoma cell lines in inducing anti-cancer effects. CONCLUSION Taken together, we have identified a drug with anti-melanoma activity in vitro and in vivo that has the potential to be combined with the standard of care agent Vemurafenib and Cobimetinib in both BRAFV600E and BRAF WT melanoma.
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Affiliation(s)
- Wei Liu
- Department of Molecular Medicine II, Medical Faculty, Heinrich-Heine-University, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Paweł Stachura
- Department of Molecular Medicine II, Medical Faculty, Heinrich-Heine-University, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Haifeng C Xu
- Department of Molecular Medicine II, Medical Faculty, Heinrich-Heine-University, Universitätsstraße 1, 40225, Düsseldorf, Germany.,Institute of Immunology, Medical Faculty, University of Duisburg-Essen, Hufelandstrasse 55, 45147, Essen, Germany
| | - Nikkitha Umesh Ganesh
- Department of Molecular Medicine II, Medical Faculty, Heinrich-Heine-University, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Fiona Cox
- Department of Molecular Medicine II, Medical Faculty, Heinrich-Heine-University, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Ruifeng Wang
- Department of Molecular Medicine II, Medical Faculty, Heinrich-Heine-University, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Karl S Lang
- Institute of Immunology, Medical Faculty, University of Duisburg-Essen, Hufelandstrasse 55, 45147, Essen, Germany
| | - Jay Gopalakrishnan
- Institute of Human Genetics, Heinrich-Heine-University, Universitätsstrasse 1, 40225, Düsseldorf, Germany
| | - Dieter Häussinger
- Department of Gastroenterology, Hepatology and Infectious Diseases, Heinrich-Heine-University, Moorenstrasse 5, 40225, Düsseldorf, Germany
| | - Bernhard Homey
- Department of Dermatology, Medical Faculty, Heinrich-Heine-University, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Philipp A Lang
- Department of Molecular Medicine II, Medical Faculty, Heinrich-Heine-University, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Aleksandra A Pandyra
- Department of Molecular Medicine II, Medical Faculty, Heinrich-Heine-University, Universitätsstraße 1, 40225, Düsseldorf, Germany. .,Department of Gastroenterology, Hepatology and Infectious Diseases, Heinrich-Heine-University, Moorenstrasse 5, 40225, Düsseldorf, Germany.
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195
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Hwang SH, Bang S, Kim W, Chung J. Von Hippel-Lindau tumor suppressor (VHL) stimulates TOR signaling by interacting with phosphoinositide 3-kinase (PI3K). J Biol Chem 2020; 295:2336-2347. [PMID: 31959630 DOI: 10.1074/jbc.ra119.011596] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 01/08/2020] [Indexed: 12/11/2022] Open
Abstract
Cell growth is positively controlled by the phosphoinositide 3-kinase (PI3K)-target of rapamycin (TOR) signaling pathway under conditions of abundant growth factors and nutrients. To discover additional mechanisms that regulate cell growth, here we performed RNAi-based mosaic analyses in the Drosophila fat body, the primary metabolic organ in the fly. Unexpectedly, the knockdown of the Drosophila von Hippel-Lindau (VHL) gene markedly decreased cell size and body size. These cell growth phenotypes induced by VHL loss of function were recovered by activation of TOR signaling in Drosophila Consistent with the genetic interactions between VHL and the signaling components of PI3K-TOR pathway in Drosophila, we observed that VHL loss of function in mammalian cells causes decreased phosphorylation of ribosomal protein S6 kinase and Akt, which represent the main activities of this pathway. We further demonstrate that VHL activates TOR signaling by directly interacting with the p110 catalytic subunit of PI3K. On the basis of the evolutionarily conserved regulation of PI3K-TOR signaling by VHL observed here, we propose that VHL plays an important role in the regulation and maintenance of proper cell growth in metazoans.
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Affiliation(s)
- Sun-Hong Hwang
- School of Biological Sciences, Seoul National University, Gwanak-Gu, Seoul 08826, Republic of Korea; Institute of Molecular Biology and Genetics, Seoul National University, Gwanak-Gu, Seoul 08826, Republic of Korea
| | - Sunhoe Bang
- School of Biological Sciences, Seoul National University, Gwanak-Gu, Seoul 08826, Republic of Korea; Institute of Molecular Biology and Genetics, Seoul National University, Gwanak-Gu, Seoul 08826, Republic of Korea
| | - Wonho Kim
- Institute of Molecular Biology and Genetics, Seoul National University, Gwanak-Gu, Seoul 08826, Republic of Korea
| | - Jongkyeong Chung
- School of Biological Sciences, Seoul National University, Gwanak-Gu, Seoul 08826, Republic of Korea; Institute of Molecular Biology and Genetics, Seoul National University, Gwanak-Gu, Seoul 08826, Republic of Korea.
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196
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Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) controls cell growth and metabolism in response to various environmental inputs, especially amino acids. In fact, the activity of mTORC1 is highly sensitive to changes in amino acid levels. Over past decades, a variety of proteins have been identified as participating in the mTORC1 pathway regulated by amino acids. Classically, the Rag guanosine triphosphatases (GTPases), which reside on the lysosome, transmit amino acid availability to the mTORC1 pathway and recruit mTORC1 to the lysosome upon amino acid sufficiency. Recently, several sensors of leucine, arginine, and S-adenosylmethionine for the amino acid-stimulated mTORC1 pathway have been coming to light. Characterization of these sensors is requisite for understanding how cells adjust amino acid sensing pathways to their different needs. In this review, we summarize recent advances in amino acid sensing mechanisms that regulate mTORC1 activity and highlight these identified sensors that accurately transmit specific amino acid signals to the mTORC1 pathway.
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Affiliation(s)
- Xiu-Zhi Li
- State Key Laboratory of Agricultural Microbiology, College of Animal Sciences and Technology, Huazhong Agricultural University, Wuhan 430070, China.,The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China.,Hubei Provincial Engineering Laboratory for Pig Precision Feeding and Feed Safety Technology, Wuhan 430070, China
| | - Xiang-Hua Yan
- State Key Laboratory of Agricultural Microbiology, College of Animal Sciences and Technology, Huazhong Agricultural University, Wuhan 430070, China.,The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China.,Hubei Provincial Engineering Laboratory for Pig Precision Feeding and Feed Safety Technology, Wuhan 430070, China
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197
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Martinez Calejman C, Trefely S, Entwisle SW, Luciano A, Jung SM, Hsiao W, Torres A, Hung CM, Li H, Snyder NW, Villén J, Wellen KE, Guertin DA. mTORC2-AKT signaling to ATP-citrate lyase drives brown adipogenesis and de novo lipogenesis. Nat Commun 2020; 11:575. [PMID: 31996678 PMCID: PMC6989638 DOI: 10.1038/s41467-020-14430-w] [Citation(s) in RCA: 79] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 12/10/2019] [Indexed: 01/09/2023] Open
Abstract
mTORC2 phosphorylates AKT in a hydrophobic motif site that is a biomarker of insulin sensitivity. In brown adipocytes, mTORC2 regulates glucose and lipid metabolism, however the mechanism has been unclear because downstream AKT signaling appears unaffected by mTORC2 loss. Here, by applying immunoblotting, targeted phosphoproteomics and metabolite profiling, we identify ATP-citrate lyase (ACLY) as a distinctly mTORC2-sensitive AKT substrate in brown preadipocytes. mTORC2 appears dispensable for most other AKT actions examined, indicating a previously unappreciated selectivity in mTORC2-AKT signaling. Rescue experiments suggest brown preadipocytes require the mTORC2/AKT/ACLY pathway to induce PPAR-gamma and establish the epigenetic landscape during differentiation. Evidence in mature brown adipocytes also suggests mTORC2 acts through ACLY to increase carbohydrate response element binding protein (ChREBP) activity, histone acetylation, and gluco-lipogenic gene expression. Substrate utilization studies additionally implicate mTORC2 in promoting acetyl-CoA synthesis from acetate through acetyl-CoA synthetase 2 (ACSS2). These data suggest that a principal mTORC2 action is controlling nuclear-cytoplasmic acetyl-CoA synthesis. mTORC2 activates Akt, a regulator of cell growth and metabolism, however, the role of mTORC2 in adipocytes is incompletely understood. Here the authors report that a mTORC2-Akt axis specifically activates ACLY to promote lipid synthesis and histone acetylation during brown adipocyte differentiation.
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Affiliation(s)
- C Martinez Calejman
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | - S Trefely
- Department of Cancer Biology, University of Pennsylvania, Philadelphia, PA, 19104, USA.,Abramson Family Cancer Research Institute, University of Pennsylvania, Philadelphia, PA, 19104, USA.,AJ Drexel Autism Institute, Drexel University, Philadelphia, PA, 19104, USA
| | - S W Entwisle
- Department of Genome Sciences, University of Washington, Seattle, WA, 98195, USA.,Program in Molecular and Cellular Biology, University of Washington, Seattle, WA, 98195, USA
| | - A Luciano
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | - S M Jung
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | - W Hsiao
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | - A Torres
- Department of Cancer Biology, University of Pennsylvania, Philadelphia, PA, 19104, USA.,Abramson Family Cancer Research Institute, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - C M Hung
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | - H Li
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | - N W Snyder
- AJ Drexel Autism Institute, Drexel University, Philadelphia, PA, 19104, USA
| | - J Villén
- Department of Genome Sciences, University of Washington, Seattle, WA, 98195, USA.,Program in Molecular and Cellular Biology, University of Washington, Seattle, WA, 98195, USA
| | - K E Wellen
- Department of Cancer Biology, University of Pennsylvania, Philadelphia, PA, 19104, USA.,Abramson Family Cancer Research Institute, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - D A Guertin
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, 01605, USA. .,Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA, 01605, USA.
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198
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Loss of TSC complex enhances gluconeogenesis via upregulation of Dlk1-Dio3 locus miRNAs. Proc Natl Acad Sci U S A 2020; 117:1524-1532. [PMID: 31919282 DOI: 10.1073/pnas.1918931117] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Loss of the tumor suppressor tuberous sclerosis complex 1 (Tsc1) in the liver promotes gluconeogenesis and glucose intolerance. We asked whether this could be attributed to aberrant expression of small RNAs. We performed small-RNA sequencing on liver of Tsc1-knockout mice, and found that miRNAs of the delta-like homolog 1 (Dlk1)-deiodinase iodothyronine type III (Dio3) locus are up-regulated in an mTORC1-dependent manner. Sustained mTORC1 signaling during development prevented CpG methylation and silencing of the Dlk1-Dio3 locus, thereby increasing miRNA transcription. Deletion of miRNAs encoded by the Dlk1-Dio3 locus reduced gluconeogenesis, glucose intolerance, and fasting blood glucose levels. Thus, miRNAs contribute to the metabolic effects observed upon loss of TSC1 and hyperactivation of mTORC1 in the liver. Furthermore, we show that miRNA is a downstream effector of hyperactive mTORC1 signaling.
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199
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Hu L, Chen Y, Cortes IM, Coleman DN, Dai H, Liang Y, Parys C, Fernandez C, Wang M, Loor JJ. Supply of methionine and arginine alters phosphorylation of mechanistic target of rapamycin (mTOR), circadian clock proteins, and α-s1-casein abundance in bovine mammary epithelial cells. Food Funct 2020; 11:883-894. [DOI: 10.1039/c9fo02379h] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Methionine (Met) and arginine (Arg) regulate casein protein abundance through alterations in activity of the mechanistic target of rapamycin complex 1 (mTORC1) signaling pathway.
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Affiliation(s)
- Liangyu Hu
- College of Animal Science and Technology
- Yangzhou University
- Yangzhou
- P.R. China
- Department of Animal Sciences and Division of Nutritional Sciences
| | - Yifei Chen
- College of Animal Science and Technology
- Yangzhou University
- Yangzhou
- P.R. China
| | - Ismael M. Cortes
- Agricultural and Animal Production Department
- UAM-Xochimilco
- Mexico City
- Mexico 04960
| | - Danielle N. Coleman
- Department of Animal Sciences and Division of Nutritional Sciences
- University of Illinois
- Urbana 61801
- USA
| | - Hongyu Dai
- Department of Animal Sciences and Division of Nutritional Sciences
- University of Illinois
- Urbana 61801
- USA
- College of Veterinary Medicine
| | - Yusheng Liang
- Department of Animal Sciences and Division of Nutritional Sciences
- University of Illinois
- Urbana 61801
- USA
| | | | - Carlos Fernandez
- Animal Science Department
- Universitàt Politècnica de Valencia
- 46022 Valencia
- Spain
| | - Mengzhi Wang
- College of Animal Science and Technology
- Yangzhou University
- Yangzhou
- P.R. China
| | - Juan J. Loor
- Department of Animal Sciences and Division of Nutritional Sciences
- University of Illinois
- Urbana 61801
- USA
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200
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Bhaoighill MN, Dunlop EA. Mechanistic target of rapamycin inhibitors: successes and challenges as cancer therapeutics. CANCER DRUG RESISTANCE (ALHAMBRA, CALIF.) 2019; 2:1069-1085. [PMID: 35582282 PMCID: PMC9019212 DOI: 10.20517/cdr.2019.87] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Revised: 11/18/2019] [Accepted: 11/26/2019] [Indexed: 12/22/2022]
Abstract
Delineating the contributions of specific cell signalling cascades to the development and maintenance of tumours has greatly informed our understanding of tumorigenesis and has advanced the modern era of targeted cancer therapy. It has been revealed that one of the key pathways regulating cell growth, the phosphatidylinositol 3-kinase/mechanistic target of rapamycin (PI3K/mTOR) signalling axis, is commonly dysregulated in cancer. With a specific, well-tolerated inhibitor of mTOR available, the impact of inhibiting this pathway at the level of mTOR has been tested clinically. This review highlights some of the promising results seen with mTOR inhibitors in the clinic and assesses some of the challenges that remain in predicting patient outcome following mTOR-targeted therapy.
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Affiliation(s)
| | - Elaine A Dunlop
- Division of Cancer and Genetics, Cardiff University, Cardiff, CF14 4XN, UK
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