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Qu H, Wang Y, Yan Q, Fan C, Zhang X, Wang D, Guo C, Chen P, Shi L, Liao Q, Zhou M, Wang F, Zeng Z, Xiang B, Xiong W. CircCDYL2 bolsters radiotherapy resistance in nasopharyngeal carcinoma by promoting RAD51 translation initiation for enhanced homologous recombination repair. J Exp Clin Cancer Res 2024; 43:122. [PMID: 38654320 PMCID: PMC11036759 DOI: 10.1186/s13046-024-03049-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Accepted: 04/17/2024] [Indexed: 04/25/2024] Open
Abstract
BACKGROUND Radiation therapy stands to be one of the primary approaches in the clinical treatment of malignant tumors. Nasopharyngeal Carcinoma, a malignancy predominantly treated with radiation therapy, provides an invaluable model for investigating the mechanisms underlying radiation therapy resistance in cancer. While some reports have suggested the involvement of circRNAs in modulating resistance to radiation therapy, the underpinning mechanisms remain unclear. METHODS RT-qPCR and in situ hybridization were used to detect the expression level of circCDYL2 in nasopharyngeal carcinoma tissue samples. The effect of circCDYL2 on radiotherapy resistance in nasopharyngeal carcinoma was demonstrated by in vitro and in vivo functional experiments. The HR-GFP reporter assay determined that circCDYL2 affected homologous recombination repair. RNA pull down, RIP, western blotting, IF, and polysome profiling assays were used to verify that circCDYL2 promoted the translation of RAD51 by binding to EIF3D protein. RESULTS We have identified circCDYL2 as highly expressed in nasopharyngeal carcinoma tissues, and it was closely associated with poor prognosis. In vitro and in vivo experiments demonstrate that circCDYL2 plays a pivotal role in promoting radiotherapy resistance in nasopharyngeal carcinoma. Our investigation unveils a specific mechanism by which circCDYL2, acting as a scaffold molecule, recruits eukaryotic translation initiation factor 3 subunit D protein (EIF3D) to the 5'-UTR of RAD51 mRNA, a crucial component of the DNA damage repair pathway to facilitate the initiation of RAD51 translation and enhance homologous recombination repair capability, and ultimately leads to radiotherapy resistance in nasopharyngeal carcinoma. CONCLUSIONS These findings establish a novel role of the circCDYL2/EIF3D/RAD51 axis in nasopharyngeal carcinoma radiotherapy resistance. Our work not only sheds light on the underlying molecular mechanism but also highlights the potential of circCDYL2 as a therapeutic sensitization target and a promising prognostic molecular marker for nasopharyngeal carcinoma.
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Affiliation(s)
- Hongke Qu
- NHC Key Laboratory of Carcinogenesis and Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410078, China
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute and School of Basic Medical Sciences, Central South University, Changsha, Hunan, 410078, China
| | - Yumin Wang
- Department of Otolaryngology Head and Neck Surgery, Xiangya Hospital, Central South University, Changsha, Hunan, 410078, China.
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan, 410078, China.
| | - Qijia Yan
- Department of Otolaryngology Head and Neck Surgery, Xiangya Hospital, Central South University, Changsha, Hunan, 410078, China
| | - Chunmei Fan
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute and School of Basic Medical Sciences, Central South University, Changsha, Hunan, 410078, China
| | - Xiangyan Zhang
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute and School of Basic Medical Sciences, Central South University, Changsha, Hunan, 410078, China
| | - Dan Wang
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute and School of Basic Medical Sciences, Central South University, Changsha, Hunan, 410078, China
| | - Can Guo
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute and School of Basic Medical Sciences, Central South University, Changsha, Hunan, 410078, China
| | - Pan Chen
- NHC Key Laboratory of Carcinogenesis and Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410078, China
| | - Lei Shi
- Department of Pathology, the Second Xiangya Hospital, Central South University, Changsha, Hunan, 410011, China
| | - Qianjin Liao
- NHC Key Laboratory of Carcinogenesis and Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410078, China
| | - Ming Zhou
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute and School of Basic Medical Sciences, Central South University, Changsha, Hunan, 410078, China
| | - Fuyan Wang
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute and School of Basic Medical Sciences, Central South University, Changsha, Hunan, 410078, China
| | - Zhaoyang Zeng
- NHC Key Laboratory of Carcinogenesis and Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410078, China
| | - Bo Xiang
- NHC Key Laboratory of Carcinogenesis and Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410078, China.
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute and School of Basic Medical Sciences, Central South University, Changsha, Hunan, 410078, China.
| | - Wei Xiong
- NHC Key Laboratory of Carcinogenesis and Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410078, China.
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute and School of Basic Medical Sciences, Central South University, Changsha, Hunan, 410078, China.
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Liu B, Lv Y, Hu W, Huang Y, Ying X, Chen C, Zhang H, Ji W. m 6A modification mediates SLC3A2/SLC7A5 translation in 3-methylcholanthrene-induced uroepithelial transformation. Cell Biol Toxicol 2024; 40:5. [PMID: 38267663 PMCID: PMC10808315 DOI: 10.1007/s10565-024-09846-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Accepted: 01/08/2024] [Indexed: 01/26/2024]
Abstract
3-Methylcholanthracene (3-MC) is one of the most carcinogenic polycyclic aromatic hydrocarbons (PAHs). Long-term exposure to PAHs has been thought of as an important factor in urothelial tumorigenesis. N6-methyladenosine (m6A) exists widely in eukaryotic organisms and regulates the expression level of specific genes by regulating mRNA stability, translation efficiency, and nuclear export efficiency. Currently, the potential molecular mechanisms that regulate m6A modification for 3-MC carcinogenesis remain unclear. Here, we profiled mRNA, m6A, translation and protein level using "-omics" methodologies, including transcriptomes, m6A profile, translatomes, and proteomics in 3-MC-transformed urothelial cells and control cells. The key molecules SLC3A2/SLC7A5 were screened and identified in 3-MC-induced uroepithelial transformation. Moreover, SLC7A5/SLC3A2 promoted uroepithelial cells malignant phenotype in vitro and in vivo. Mechanically, METTL3 and ALKBH5 mediated m6A modification of SLC3A2/SLC7A5 mRNA in 3-MC-induced uroepithelial transformation by upregulating the translation of SLC3A2/SLC7A5. Furthermore, programmable m6A modification of SLC3A2/SLC7A5 mRNA affected the expression of its proteins. Taken together, our results revealed that the m6A modification-mediated SLC3A2/SLC7A5 translation promoted 3-MC-induced uroepithelial transformation, suggesting that targeting m6A modification of SLC3A2/SLC7A5 may be a potential therapeutic strategy for bladder cancer related to PAHs.
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Affiliation(s)
- Bixia Liu
- Center for Translational Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, China
- Department of Pathology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, 510080, China
| | - Yifan Lv
- Department of Urology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510080, China
| | - Wenyu Hu
- Center for Translational Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, China
| | - Yapeng Huang
- Center for Translational Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, China
| | - Xiaoling Ying
- Department of Urology, The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510080, China
| | - Cong Chen
- Center for Translational Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, China
| | - Haiqing Zhang
- Center for Translational Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, China
| | - Weidong Ji
- Center for Translational Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, China.
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3
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Proteomic Analysis of Lung Cancer Types—A Pilot Study. Cancers (Basel) 2022; 14:cancers14112629. [PMID: 35681609 PMCID: PMC9179298 DOI: 10.3390/cancers14112629] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 05/21/2022] [Accepted: 05/25/2022] [Indexed: 12/12/2022] Open
Abstract
Lung cancer is the leading cause of tumor-related mortality, therefore significant effort is directed towards understanding molecular alterations occurring at the origin of the disease to improve current treatment options. The aim of our pilot-scale study was to carry out a detailed proteomic analysis of formalin-fixed paraffin-embedded tissue sections from patients with small cell or non-small cell lung cancer (adenocarcinoma, squamous cell carcinoma, and large cell carcinoma). Tissue surface digestion was performed on relatively small cancerous and tumor-adjacent normal regions and differentially expressed proteins were identified using label-free quantitative mass spectrometry and subsequent statistical analysis. Principal component analysis clearly distinguished cancerous and cancer adjacent normal samples, while the four lung cancer types investigated had distinct molecular profiles and gene set enrichment analysis revealed specific dysregulated biological processes as well. Furthermore, proteins with altered expression unique to a specific lung cancer type were identified and could be the targets of future studies.
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Shen C, He Y, Chen Q, Feng H, Williams TM, Lu Y, He Z. Narrative review of emerging roles for AKT-mTOR signaling in cancer radioimmunotherapy. ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:1596. [PMID: 34790802 PMCID: PMC8576660 DOI: 10.21037/atm-21-4544] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 09/27/2021] [Indexed: 12/20/2022]
Abstract
Objective To summarize the roles of AKT-mTOR signaling in the regulation of the DNA damage response and PD-L1 expression in cancer cells, and propose a novel strategy of targeting AKT-mTOR signaling in combination with radioimmunotherapy in the era of cancer immunotherapy Background Immunotherapy has greatly improved the clinical outcomes of many cancer patients and has changed the landscape of cancer patient management. However, only a small subgroup of cancer patients (~20–30%) benefit from immune checkpoint blockade-based immunotherapy. The current challenge is to find biomarkers to predict the response of patients to immunotherapy and strategies to sensitize patients to immunotherapy. Methods Search and review the literature which were published in PUBMED from 2000–2021 with the key words mTOR, AKT, drug resistance, DNA damage response, immunotherapy, PD-L1, DNA repair, radioimmunotherapy. Conclusions More than 50% of cancer patients receive radiotherapy during their course of treatment. Radiotherapy has been shown to reduce the growth of locally irradiated tumors as well as metastatic non-irradiated tumors (abscopal effects) by affecting systemic immunity. Consistently, immunotherapy has been demonstrated to enhance radiotherapy with more than one hundred clinical trials of radiation in combination with immunotherapy (radioimmunotherapy) across cancer types. Nevertheless, current available data have shown limited efficacy of trials testing radioimmunotherapy. AKT-mTOR signaling is a major tumor growth-promoting pathway and is upregulated in most cancers. AKT-mTOR signaling is activated by growth factors as well as genotoxic stresses including radiotherapy. Importantly, recent advances have shown that AKT-mTOR is one of the main signaling pathways that regulate DNA damage repair as well as PD-L1 levels in cancers. These recent advances clearly suggest a novel cancer therapy strategy by targeting AKT-mTOR signaling in combination with radioimmunotherapy.
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Affiliation(s)
- Changxian Shen
- Department of Radiation Oncology, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA, USA
| | - Yuqi He
- Monash School of Medicine, Monash University, Clayton, VIC, Australia
| | - Qiang Chen
- Department of Oncology, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Haihua Feng
- Department of Radiation Oncology, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA, USA
| | - Terence M Williams
- Department of Radiation Oncology, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA, USA
| | - Yuanzhi Lu
- Department of Clinical Pathology, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Zhengfu He
- Department of Thoracic Surgery, Sir Run Run Shaw Hospital, College of Medicine Zhejiang University, Hangzhou, China
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5
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Takahashi S. Kinase Inhibitors and Interferons as Other Myeloid Differentiation Inducers in Leukemia Therapy. Acta Haematol 2021; 145:113-121. [PMID: 34673646 DOI: 10.1159/000519769] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 09/20/2021] [Indexed: 12/26/2022]
Abstract
Differentiation therapy using all-trans retinoic acid (ATRA) is well established for the treatment of acute promyelocytic leukemia (APL). Several attempts have been made to treat non-APL acute myeloid leukemia (AML) patients by employing differentiation inducers, such as hypomethylating agents and low-dose cytarabine, with encouraging results. In the present review, I focus on other possible differentiation inducers: kinase inhibitors and interferons (IFNs). A number of kinase inhibitors have been reported to induce differentiation, including CDK inhibitors, GSK3 inhibitors, Akt inhibitors, p38 MAPK inhibitors, Src family kinase inhibitors, Syk inhibitors, mTOR inhibitors, and HSP90 inhibitors. Other powerful inducers are IFNs, which were reported to enhance differentiation with ATRA. Although clinical trials for these kinase modulators remain scarce, their mechanisms of action have been, at least partly, clarified. The Raf/MEK/ERK MAPK pathway and the RARα downstream are affected by many of the kinase inhibitors and IFNs and seem to play a pivotal role for the induction of myeloid differentiation. Further clarification of the mechanisms, as well as the establishment of efficient combination therapies with the kinase inhibitors or IFNs, may lead to the development of effective therapeutic strategies for AML.
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Affiliation(s)
- Shinichiro Takahashi
- Division of Laboratory Medicine, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, Sendai, Japan
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6
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Biguanides drugs: Past success stories and promising future for drug discovery. Eur J Med Chem 2021; 224:113726. [PMID: 34364161 DOI: 10.1016/j.ejmech.2021.113726] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 07/27/2021] [Accepted: 07/27/2021] [Indexed: 12/13/2022]
Abstract
Biguanides have attracted much attention a century ago and showed resurgent interest in recent years after a long period of dormancy. They constitute an important class of therapeutic agents suitable for the treatment of a wide spectrum of diseases. Therapeutic indications of biguanides include antidiabetic, antimalarial, antiviral, antiplaque, and bactericidal applications. This review presents an extensive overview of the biological activity of biguanides and different mechanisms of action of currently marketed biguanide-containing drugs, as well as their pharmacological properties when applicable. We highlight the recent developments in research on biguanide compounds, with a primary focus on studies on metformin in the field of oncology. We aim to provide a critical overview of all main bioactive biguanide compounds and discuss future perspectives for the design of new drugs based on the biguanide fragment.
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7
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Butler M, van der Meer LT, van Leeuwen FN. Amino Acid Depletion Therapies: Starving Cancer Cells to Death. Trends Endocrinol Metab 2021; 32:367-381. [PMID: 33795176 DOI: 10.1016/j.tem.2021.03.003] [Citation(s) in RCA: 109] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 02/25/2021] [Accepted: 03/09/2021] [Indexed: 01/01/2023]
Abstract
Targeting tumor cell metabolism is an attractive form of therapy, as it may enhance treatment response in therapy resistant cancers as well as mitigate treatment-related toxicities by reducing the need for genotoxic agents. To meet their increased demand for biomass accumulation and energy production and to maintain redox homeostasis, tumor cells undergo profound changes in their metabolism. In addition to the diversion of glucose metabolism, this is achieved by upregulation of amino acid metabolism. Interfering with amino acid availability can be selectively lethal to tumor cells and has proven to be a cancer specific Achilles' heel. Here we review the biology behind such cancer specific amino acid dependencies and discuss how these vulnerabilities can be exploited to improve cancer therapies.
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Affiliation(s)
- Miriam Butler
- Princess Máxima Center for Pediatric Oncology, Utrecht, The Netherlands; Laboratory of Pediatric Oncology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands
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8
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He Z, Houghton PJ, Williams TM, Shen C. Regulation of DNA duplication by the mTOR signaling pathway. Cell Cycle 2021; 20:742-751. [PMID: 33691584 DOI: 10.1080/15384101.2021.1897271] [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] [Indexed: 10/21/2022] Open
Abstract
Accurate and complete DNA replication and separation are essential for genetic information inheritance and organism maintenance. Errors in DNA duplication are the main source of genetic instability. Understanding DNA duplication regulation is the key to elucidate the mechanisms and find treatment strategies for human genetic disorders, especially cancer. The mechanistic target of rapamycin (mTOR) is a central regulator of cell growth and proliferation by integrating and processing extracellular and intracellular signals to monitor the well-being of cell physiology. mTOR signaling dysregulation is associated with many human diseases including cancer and diabetes. Emerging evidence has demonstrated that mTOR signaling plays a key role in DNA duplication. We herein review the current knowledge of mTOR signaling in the regulation of DNA replication origin licensing, replication fork progression, and stabilization.
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Affiliation(s)
- Zhengfu He
- Department of Thoracic Surgery, Sir Run Run Shaw Hospital, College of Medicine Zhejiang University, Hangzhou, China
| | - Peter J Houghton
- The Greehey Children's Cancer Research Institute, the University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| | - Terence M Williams
- Department of Radiation Oncology, Beckman Research Institute, City of Hope National Medical Center, Duarte, California, USA
| | - Changxian Shen
- Department of Radiation Oncology, Beckman Research Institute, City of Hope National Medical Center, Duarte, California, USA
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9
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Song P, Yang F, Jin H, Wang X. The regulation of protein translation and its implications for cancer. Signal Transduct Target Ther 2021; 6:68. [PMID: 33597534 PMCID: PMC7889628 DOI: 10.1038/s41392-020-00444-9] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Revised: 08/30/2020] [Accepted: 12/06/2020] [Indexed: 02/08/2023] Open
Abstract
In addition to the deregulation of gene transcriptions and post-translational protein modifications, the aberrant translation from mRNAs to proteins plays an important role in the pathogenesis of various cancers. Targeting mRNA translation are expected to become potential approaches for anticancer treatments. Protein translation is affected by many factors including translation initiation factors and RNA-binding proteins. Recently, modifications of mRNAs mainly N6-methyladenine (m6A) modification and noncoding RNAs, such as microRNAs and long noncoding RNAs are involved. In this review, we generally summarized the recent advances on the regulation of protein translation by the interplay between mRNA modifications and ncRNAs. By doing so, we hope this review could offer some hints for the development of novel approaches in precision therapy of human cancers.
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Affiliation(s)
- Ping Song
- grid.13402.340000 0004 1759 700XDepartment of Medical Oncology, Cancer Institute of Zhejiang University, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang China
| | - Fan Yang
- grid.13402.340000 0004 1759 700XDepartment of Hepatobiliary and Pancreatic Surgery, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang China
| | - Hongchuan Jin
- grid.13402.340000 0004 1759 700XKey Lab of Biotherapy in Zhejiang, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang China
| | - Xian Wang
- grid.13402.340000 0004 1759 700XDepartment of Medical Oncology, Cancer Institute of Zhejiang University, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang China
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10
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Yoon MS. Nanotechnology-Based Targeting of mTOR Signaling in Cancer. Int J Nanomedicine 2020; 15:5767-5781. [PMID: 32821100 PMCID: PMC7418174 DOI: 10.2147/ijn.s254574] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 05/13/2020] [Indexed: 12/20/2022] Open
Abstract
Mammalian target of rapamycin (mTOR) is a master regulator of cell growth and metabolism, which is activated in response to intra- and extracellular signals, including nutrients, growth factors, and cellular energy levels. The frequent dysregulation of mTOR signaling in cancer makes it an attractive therapeutic target, and several types of mTOR inhibitors have been developed. Nanoparticle-based mTOR modulators are predicted to target various cancers and deliver as well as release drugs in a controlled manner, resulting in enhanced bioavailability and reduced side effects. This mini-review is focused on the molecular mechanism of nanoparticle-based mTOR modulator action as well as the current development of mTOR inhibitors using nanoparticles. Understanding the biological function of nanoparticle-based mTOR modulators will contribute to the development of efficient nano-therapeutics for the treatment of cancers.
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Affiliation(s)
- Mee-Sup Yoon
- Department of Molecular Medicine, School of Medicine, Lee Gil Ya Cancer and Diabetes Institute, Department of Health Sciences and Technology, GAIHST, Gachon University, Incheon 21999, Republic of Korea
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11
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Gary JM, Simmons JK, Xu J, Zhang S, Peat TJ, Watson N, Gamache BJ, Zhang K, Kovalchuk AL, Michalowski AM, Chen JQ, Thaiwong T, Kiupel M, Gaikwad S, Etienne M, Simpson RM, Dubois W, Testa JR, Mock BA. Hypomorphic mTOR Downregulates CDK6 and Delays Thymic Pre-T LBL Tumorigenesis. Mol Cancer Ther 2020; 19:2221-2232. [PMID: 32747423 DOI: 10.1158/1535-7163.mct-19-0671] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 01/14/2020] [Accepted: 07/13/2020] [Indexed: 11/16/2022]
Abstract
PI3K/AKT/mTOR pathway hyperactivation is frequent in T-cell acute lymphoblastic leukemia/lymphoma (T-ALL/LBL). To model inhibition of mTOR, pre-T-cell lymphoblastic leukemia/lymphoma (pre-T LBL) tumor development was monitored in mice with T lymphocyte-specific, constitutively active AKT (Lck-MyrAkt2) that were either crossed to mTOR knockdown (KD) mice or treated with the mTOR inhibitor everolimus. Lck-MyrAkt2;mTOR KD mice lived significantly longer than Lck-MyrAkt2;mTOR wild-type (WT) mice, although both groups ultimately developed thymic pre-T LBL. An increase in survival was also observed when Lck-MyrAkt2;mTOR WT mice were treated for 8 weeks with everolimus. The transcriptional profiles of WT and KD thymic lymphomas were compared, and Ingenuity Pathway Upstream Regulator Analysis of differentially expressed genes in tumors from mTOR WT versus KD mice identified let-7 and miR-21 as potential regulatory genes. mTOR KD mice had higher levels of let-7a and miR-21 than mTOR WT mice, and rapamycin induced their expression in mTOR WT cells. CDK6 was one of the most downregulated targets of both let-7 and miR21 in mTOR KD tumors. CDK6 overexpression and decreased expression of let-7 in mTOR KD cells rescued a G1 arrest phenotype. Combined mTOR (rapamycin) and CDK4/6 (palbociclib) inhibition decreased tumor size and proliferation in tumor flank transplants, increased survival in an intravenous transplant model of disseminated leukemia compared with single agent treatment, and cooperatively decreased cell viability in human T-ALL/LBL cell lines. Thus, mTOR KD mice provide a model to explore drug combinations synergizing with mTOR inhibitors and can be used to identify downstream targets of inhibition.
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Affiliation(s)
- Joy M Gary
- Laboratory of Cancer Biology and Genetics, CCR, NCI, NIH, Bethesda, Maryland.,Pathobiology and Diagnostic Investigation, Michigan State University, East Lansing, Michigan
| | - John K Simmons
- Laboratory of Cancer Biology and Genetics, CCR, NCI, NIH, Bethesda, Maryland
| | - Jinfei Xu
- Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Shuling Zhang
- Laboratory of Cancer Biology and Genetics, CCR, NCI, NIH, Bethesda, Maryland
| | - Tyler J Peat
- Laboratory of Cancer Biology and Genetics, CCR, NCI, NIH, Bethesda, Maryland
| | - Nicholas Watson
- Laboratory of Cancer Biology and Genetics, CCR, NCI, NIH, Bethesda, Maryland
| | - Benjamin J Gamache
- Laboratory of Cancer Biology and Genetics, CCR, NCI, NIH, Bethesda, Maryland.,American University, Washington, DC
| | - Ke Zhang
- Laboratory of Cancer Biology and Genetics, CCR, NCI, NIH, Bethesda, Maryland
| | | | | | - Jin-Qiu Chen
- Laboratory of Cancer Biology and Genetics, CCR, NCI, NIH, Bethesda, Maryland
| | - Tuddow Thaiwong
- Pathobiology and Diagnostic Investigation, Michigan State University, East Lansing, Michigan
| | - Matti Kiupel
- Pathobiology and Diagnostic Investigation, Michigan State University, East Lansing, Michigan
| | - Snehal Gaikwad
- Laboratory of Cancer Biology and Genetics, CCR, NCI, NIH, Bethesda, Maryland
| | - Maudeline Etienne
- Laboratory of Cancer Biology and Genetics, CCR, NCI, NIH, Bethesda, Maryland
| | - R Mark Simpson
- Laboratory of Cancer Biology and Genetics, CCR, NCI, NIH, Bethesda, Maryland
| | - Wendy Dubois
- Laboratory of Cancer Biology and Genetics, CCR, NCI, NIH, Bethesda, Maryland
| | - Joseph R Testa
- Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania.
| | - Beverly A Mock
- Laboratory of Cancer Biology and Genetics, CCR, NCI, NIH, Bethesda, Maryland.
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12
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Pietropaolo V, Prezioso C, Moens U. Merkel Cell Polyomavirus and Merkel Cell Carcinoma. Cancers (Basel) 2020; 12:E1774. [PMID: 32635198 PMCID: PMC7407210 DOI: 10.3390/cancers12071774] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 06/26/2020] [Accepted: 06/28/2020] [Indexed: 12/12/2022] Open
Abstract
Viruses are the cause of approximately 15% of all human cancers. Both RNA and DNA human tumor viruses have been identified, with Merkel cell polyomavirus being the most recent one to be linked to cancer. This virus is associated with about 80% of Merkel cell carcinomas, a rare, but aggressive cutaneous malignancy. Despite its name, the cells of origin of this tumor may not be Merkel cells. This review provides an update on the structure and life cycle, cell tropism and epidemiology of the virus and its oncogenic properties. Putative strategies to prevent viral infection or treat virus-positive Merkel cell carcinoma patients are discussed.
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Affiliation(s)
- Valeria Pietropaolo
- Department of Public Health and Infectious Diseases, “Sapienza” University, 00185 Rome, Italy; (V.P.); (C.P.)
| | - Carla Prezioso
- Department of Public Health and Infectious Diseases, “Sapienza” University, 00185 Rome, Italy; (V.P.); (C.P.)
- IRCSS San Raffaele Pisana, Microbiology of Chronic Neuro-Degenerative Pathologies, 00166 Rome, Italy
| | - Ugo Moens
- Molecular Inflammation Research Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø—The Arctic University of Norway, 9037 Tromsø, Norway
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13
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Link AJ, Niu X, Weaver CM, Jennings JL, Duncan DT, McAfee KJ, Sammons M, Gerbasi VR, Farley AR, Fleischer TC, Browne CM, Samir P, Galassie A, Boone B. Targeted Identification of Protein Interactions in Eukaryotic mRNA Translation. Proteomics 2020; 20:e1900177. [PMID: 32027465 DOI: 10.1002/pmic.201900177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 12/13/2019] [Indexed: 11/09/2022]
Abstract
To identify protein-protein interactions and phosphorylated amino acid sites in eukaryotic mRNA translation, replicate TAP-MudPIT and control experiments are performed targeting Saccharomyces cerevisiae genes previously implicated in eukaryotic mRNA translation by their genetic and/or functional roles in translation initiation, elongation, termination, or interactions with ribosomal complexes. Replicate tandem affinity purifications of each targeted yeast TAP-tagged mRNA translation protein coupled with multidimensional liquid chromatography and tandem mass spectrometry analysis are used to identify and quantify copurifying proteins. To improve sensitivity and minimize spurious, nonspecific interactions, a novel cross-validation approach is employed to identify the most statistically significant protein-protein interactions. Using experimental and computational strategies discussed herein, the previously described protein composition of the canonical eukaryotic mRNA translation initiation, elongation, and termination complexes is calculated. In addition, statistically significant unpublished protein interactions and phosphorylation sites for S. cerevisiae's mRNA translation proteins and complexes are identified.
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Affiliation(s)
- Andrew J Link
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA.,Department of Biochemistry, Vanderbilt University, Nashville, TN, 37232, USA.,Department of Chemistry, Vanderbilt University, Nashville, TN, 37232, USA
| | - Xinnan Niu
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Connie M Weaver
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Jennifer L Jennings
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Dexter T Duncan
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - K Jill McAfee
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Morgan Sammons
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, 37232, USA
| | - Vince R Gerbasi
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Adam R Farley
- Department of Biochemistry, Vanderbilt University, Nashville, TN, 37232, USA
| | - Tracey C Fleischer
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | | | - Parimal Samir
- Department of Biochemistry, Vanderbilt University, Nashville, TN, 37232, USA
| | - Allison Galassie
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37232, USA
| | - Braden Boone
- Department of Bioinformatics, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
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14
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Daicho K, Koike N, Ott RG, Daum G, Ushimaru T. TORC1 ensures membrane trafficking of Tat2 tryptophan permease via a novel transcriptional activator Vhr2 in budding yeast. Cell Signal 2020; 68:109542. [PMID: 31954176 DOI: 10.1016/j.cellsig.2020.109542] [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: 11/07/2019] [Revised: 01/14/2020] [Accepted: 01/14/2020] [Indexed: 10/25/2022]
Abstract
The target of rapamycin complex 1 (TORC1) protein kinase is activated by nutrients and controls nutrient uptake via the membrane trafficking of various nutrient permeases. However, its molecular mechanisms remain elusive. Cholesterol (ergosterol in yeast) in conjunction with sphingolipids forms tight-packing microdomains, "lipid rafts", which are critical for intracellular protein sorting. Here we show that a novel target of rapamycin (TOR)-interacting transcriptional activator Vhr2 is required for full expression of some ERG genes for ergosterol biogenesis and for proper sorting of the tryptophan permease Tat2 in budding yeast. Loss of Vhr2 caused sterol biogenesis disturbance and Tat2 missorting. TORC1 activity maintained VHR2 transcript and protein levels, and total sterol levels. Vhr2 was not involved in regulation of the TORC1-downstream protein kinase Npr1, which regulates Tat2 sorting. This study suggests that TORC1 regulates nutrient uptake via sterol biogenesis.
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Affiliation(s)
- Katsue Daicho
- Biological Science, Graduate School of Science, Shizuoka University, Ohya 836, Suruga-ku, Shizuoka 422-8021, Japan
| | - Naoki Koike
- Graduate School of Science and Technology, Shizuoka University, Ohya 836, Suruga-ku, Shizuoka 422-8021, Japan
| | - René Georg Ott
- Institut für Biochemie, Technische Universität Graz, Petersgasse 12/2, A-8010 Graz, Austria
| | - Günther Daum
- Institut für Biochemie, Technische Universität Graz, Petersgasse 12/2, A-8010 Graz, Austria
| | - Takashi Ushimaru
- Biological Science, Graduate School of Science, Shizuoka University, Ohya 836, Suruga-ku, Shizuoka 422-8021, Japan; Graduate School of Science and Technology, Shizuoka University, Ohya 836, Suruga-ku, Shizuoka 422-8021, Japan.
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15
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Guo B, Wu S, Zhu X, Zhang L, Deng J, Li F, Wang Y, Zhang S, Wu R, Lu J, Zhou Y. Micropeptide CIP2A-BP encoded by LINC00665 inhibits triple-negative breast cancer progression. EMBO J 2020; 39:e102190. [PMID: 31755573 PMCID: PMC6939193 DOI: 10.15252/embj.2019102190] [Citation(s) in RCA: 135] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2019] [Revised: 10/10/2019] [Accepted: 10/15/2019] [Indexed: 01/22/2023] Open
Abstract
TGF-β signaling pathway plays a key role in breast cancer metastasis. Recent studies suggest that TGF-β regulates tumor progression and invasion not only via transcriptional regulation, but also via translational regulation. Using both bioinformatics and experimental tools, we identified a micropeptide CIP2A-BP encoded by LINC00665, whose translation was downregulated by TGF-β in breast cancer cell lines. Using TNBC cell lines, we showed that TGF-β-activated Smad signaling pathway induced the expression of translation inhibitory protein 4E-BP1, which inhibited eukaryote translation initiation factor elF4E, leading to reduced translation of CIP2A-BP from LINC00665. CIP2A-BP directly binds tumor oncogene CIP2A to replace PP2A's B56γ subunit, thus releasing PP2A activity, which inhibits PI3K/AKT/NFκB pathway, resulting in decreased expression levels of MMP-2, MMP-9, and Snail. Downregulation of CIP2A-BP in TNBC patients was significantly associated with metastasis and poor overall survival. In the MMTV-PyMT model, either introducing CIP2A-BP gene or direct injection of CIP2A-BP micropeptide significantly reduced lung metastases and improved overall survival. In conclusion, we provide evidence that CIP2A-BP is both a prognostic marker and a novel therapeutic target for TNBC.
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Affiliation(s)
- Binbin Guo
- Department of GeneticsMedical College of Soochow UniversitySuzhouChina
| | - Siqi Wu
- Department of GeneticsMedical College of Soochow UniversitySuzhouChina
| | - Xun Zhu
- Department of General SurgeryThe Second Affiliated Hospital of Soochow UniversitySuzhouChina
| | - Liyuan Zhang
- Department of Radiotherapy & OncologyThe Second Affiliated Hospital of Soochow UniversitySuzhouChina
| | - Jieqiong Deng
- Department of GeneticsMedical College of Soochow UniversitySuzhouChina
| | - Fang Li
- Department of GeneticsMedical College of Soochow UniversitySuzhouChina
| | - Yirong Wang
- Department of GeneticsMedical College of Soochow UniversitySuzhouChina
| | - Shenghua Zhang
- Department of GeneticsMedical College of Soochow UniversitySuzhouChina
| | - Rui Wu
- Department of GeneticsMedical College of Soochow UniversitySuzhouChina
| | - Jiachun Lu
- The State Key Lab of Respiratory DiseaseThe First Affiliated HospitalThe School of Public HealthGuangzhou Medical UniversityGuangzhouChina
| | - Yifeng Zhou
- Department of GeneticsMedical College of Soochow UniversitySuzhouChina
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16
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Zhang H, Wang A, Tan Y, Wang S, Ma Q, Chen X, He Z. NCBP1 promotes the development of lung adenocarcinoma through up-regulation of CUL4B. J Cell Mol Med 2019; 23:6965-6977. [PMID: 31448526 PMCID: PMC6787490 DOI: 10.1111/jcmm.14581] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Revised: 06/06/2019] [Accepted: 06/24/2019] [Indexed: 01/01/2023] Open
Abstract
Lung cancer is the most frequent cancer type and is the leading cause of tumour‐associated deaths worldwide. Nuclear cap‐binding protein 1 (NCBP1) is necessary for capped RNA processing and intracellular localization. It has been reported that silencing of NCBP1 resulted in cell growth reduction in HeLa cells. Nevertheless, its clinical significance and underlying molecular mechanisms in non–small‐cell lung cancer remain unclear. In this study, we found that NCBP1 was significantly overexpressed in lung cancer tissues and several lung cancer cell lines. Through knockdown and overexpression experiments, we showed that NCBP1 promoted lung cancer cell growth, wound healing ability, migration and epithelial‐mesenchymal transition. Mechanistically, we found that cullin 4B (CUL4B) was a downstream target gene of NCBP1 in NSCLC. NCBP1 up‐regulated CUL4B expression via interaction with nuclear cap‐binding protein 3 (NCBP3). CUL4B silencing significantly reversed NCBP1‐induced tumorigenesis in vitro. Based on these findings, we propose a model involving the NCBP1‐NCBP3‐CUL4B oncoprotein axis, providing novel insight into how CUL4B is activated and contributes to LUAD progression.
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Affiliation(s)
- Huijun Zhang
- Department of Cardiothoracic Surgery, Huashan Hospital of Fudan University, Shanghai, China
| | - An Wang
- Department of Cardiothoracic Surgery, Huashan Hospital of Fudan University, Shanghai, China
| | - Yulong Tan
- Department of Cardiothoracic Surgery, Huashan Hospital of Fudan University, Shanghai, China
| | - Shaohua Wang
- Department of Cardiothoracic Surgery, Huashan Hospital of Fudan University, Shanghai, China
| | - Qinyun Ma
- Department of Cardiothoracic Surgery, Huashan Hospital of Fudan University, Shanghai, China
| | - Xiaofeng Chen
- Department of Cardiothoracic Surgery, Huashan Hospital of Fudan University, Shanghai, China
| | - Zelai He
- Department of Radiation Oncology, The First Affiliated Hospital of Bengbu Medical College, Bengbu, China
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17
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Moens U, Macdonald A. Effect of the Large and Small T-Antigens of Human Polyomaviruses on Signaling Pathways. Int J Mol Sci 2019; 20:ijms20163914. [PMID: 31408949 PMCID: PMC6720190 DOI: 10.3390/ijms20163914] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 08/09/2019] [Accepted: 08/10/2019] [Indexed: 12/12/2022] Open
Abstract
Viruses are intracellular parasites that require a permissive host cell to express the viral genome and to produce new progeny virus particles. However, not all viral infections are productive and some viruses can induce carcinogenesis. Irrespective of the type of infection (productive or neoplastic), viruses hijack the host cell machinery to permit optimal viral replication or to transform the infected cell into a tumor cell. One mechanism viruses employ to reprogram the host cell is through interference with signaling pathways. Polyomaviruses are naked, double-stranded DNA viruses whose genome encodes the regulatory proteins large T-antigen and small t-antigen, and structural proteins that form the capsid. The large T-antigens and small t-antigens can interfere with several host signaling pathways. In this case, we review the interplay between the large T-antigens and small t-antigens with host signaling pathways and the biological consequences of these interactions.
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Affiliation(s)
- Ugo Moens
- Molecular Inflammation Research Group, Department of Medical Biology, Faculty of Health Sciences, UiT The Arctic University of Norway, 9019 Tromsø, Norway.
| | - Andrew Macdonald
- School of Molecular and Cellular Biology, Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.
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18
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Harms PW, Harms KL, Moore PS, DeCaprio JA, Nghiem P, Wong MKK, Brownell I. The biology and treatment of Merkel cell carcinoma: current understanding and research priorities. Nat Rev Clin Oncol 2019; 15:763-776. [PMID: 30287935 PMCID: PMC6319370 DOI: 10.1038/s41571-018-0103-2] [Citation(s) in RCA: 176] [Impact Index Per Article: 35.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Merkel cell carcinoma (MCC) is a rare and aggressive skin cancer associated with advanced age and immunosuppression. Over the past decade, an association has been discovered between MCC and either integration of the Merkel cell polyomavirus, which likely drives tumorigenesis, or somatic mutations owing to ultraviolet-induced DNA damage. Both virus-positive and virus-negative MCCs are immunogenic, and inhibition of the programmed cell death protein 1 (PD-1)–programmed cell death 1 ligand 1 (PD-L1) immune checkpoint has proved to be highly effective in treating patients with metastatic MCC; however, not all patients have a durable response to immunotherapy. Despite these rapid advances in the understanding and management of patients with MCC, many basic, translational and clinical research questions remain unanswered. In March 2018, an International Workshop on Merkel Cell Carcinoma Research was held at the US National Cancer Institute, at which academic, government and industry experts met to identify the highest-priority research questions. Here, we review the biology and treatment of MCC and report the consensus-based recommendations agreed upon during the workshop. Merkel cell carcinoma (MCC) is a rare and aggressive form of nonmelanoma skin cancer. The availability of immune checkpoint inhibition has improved the outcomes of a subset of patients with MCC, although many unmet needs continue to exist. In this Consensus Statement, the authors summarize developments in our understanding of MCC while also providing consensus recommendations for future research.
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Affiliation(s)
- Paul W Harms
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Kelly L Harms
- Department of Dermatology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Patrick S Moore
- Cancer Virology Program, University of Pittsburgh, Pittsburgh, PA, USA
| | - James A DeCaprio
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Paul Nghiem
- Department of Medicine, Division of Dermatology, University of Washington, Seattle, WA, USA
| | - Michael K K Wong
- Department of Melanoma Medical Oncology, Division of Cancer Medicine, MD Anderson Cancer Center, Houston, TX, USA
| | - Isaac Brownell
- Dermatology Branch, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) and National Cancer Institute (NCI), NIH, Bethesda, MD, USA.
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19
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Sriram A, Bohlen J, Teleman AA. Translation acrobatics: how cancer cells exploit alternate modes of translational initiation. EMBO Rep 2018; 19:embr.201845947. [PMID: 30224410 DOI: 10.15252/embr.201845947] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 07/09/2018] [Accepted: 08/16/2018] [Indexed: 12/11/2022] Open
Abstract
Recent work has brought to light many different mechanisms of translation initiation that function in cells in parallel to canonical cap-dependent initiation. This has important implications for cancer. Canonical cap-dependent translation initiation is inhibited by many stresses such as hypoxia, nutrient limitation, proteotoxic stress, or genotoxic stress. Since cancer cells are often exposed to these stresses, they rely on alternate modes of translation initiation for protein synthesis and cell growth. Cancer mutations are now being identified in components of the translation machinery and in cis-regulatory elements of mRNAs, which both control translation of cancer-relevant genes. In this review, we provide an overview on the various modes of non-canonical translation initiation, such as leaky scanning, translation re-initiation, ribosome shunting, IRES-dependent translation, and m6A-dependent translation, and then discuss the influence of stress on these different modes of translation. Finally, we present examples of how these modes of translation are dysregulated in cancer cells, allowing them to grow, to proliferate, and to survive, thereby highlighting the importance of translational control in cancer.
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Affiliation(s)
- Ashwin Sriram
- German Cancer Research Center (DKFZ), Heidelberg, Germany.,Heidelberg University, Heidelberg, Germany
| | - Jonathan Bohlen
- German Cancer Research Center (DKFZ), Heidelberg, Germany.,Heidelberg University, Heidelberg, Germany
| | - Aurelio A Teleman
- German Cancer Research Center (DKFZ), Heidelberg, Germany .,Heidelberg University, Heidelberg, Germany
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20
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Min Z, Tang Y, Hu XT, Zhu BL, Ma YL, Zha JS, Deng XJ, Yan Z, Chen GJ. Cosmosiin Increases ADAM10 Expression via Mechanisms Involving 5'UTR and PI3K Signaling. Front Mol Neurosci 2018; 11:198. [PMID: 29942252 PMCID: PMC6004422 DOI: 10.3389/fnmol.2018.00198] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Accepted: 05/18/2018] [Indexed: 12/13/2022] Open
Abstract
The α-secretase “a disintegrin and metalloproteinase domain-containing protein” (ADAM10) is involved in the processing of amyloid precursor protein (APP). Upregulation of ADAM10 precludes the generation of neurotoxic β-amyloid protein (Aβ) and represents a plausible therapeutic strategy for Alzheimer’s disease (AD). In this study, we explored compounds that can potentially promote the expression of ADAM10. Therefore, we performed high-throughput small-molecule screening in SH-SY5Y (human neuroblastoma) cells that stably express a luciferase reporter gene driven by the ADAM10 promoter, including a portion of its 5’-untranslated region (5’UTR). This has led to the discovery of cosmosiin (apigenin 7-O-β-glucoside). Here, we report that in human cell lines (SH-SY5Y and HEK293), cosmosiin proportionally increased the levels of the immature and mature forms of the ADAM10 protein without altering its mRNA level. This effect was attenuated by translation inhibitors or by deleting the 5’UTR of ADAM10, suggesting that a translational mechanism was responsible for the increased levels of ADAM10. Luciferase deletion assays revealed that the first 144 nucleotides of the 5’UTR were necessary for mediating the cosmosiin-induced enhancement of ADAM10 expression in SH-SY5Y cells. Cosmosiin failed to increase the levels of the ADAM10 protein in murine cells, which lack native expression of the ADAM10 transcript containing the identified 5’UTR element. The potential signaling pathway may involve phosphatidylinositide 3-kinase (PI3K) because pharmacological inhibition of PI3K attenuated the effect of cosmosiin on the expression of the ADAM10 protein. Finally, cosmosiin attenuated Aβ generation because the levels of Aβ40/42 in HEK-APP cells were significantly reduced after cosmosiin treatment. Collectively, we found that the first 144 nucleotides of the ADAM10 5’UTR, and PI3K signaling, are involved in cosmosiin-induced enhancement of the expression of ADAM10 protein. These results suggest that cosmosiin may be a potential therapeutic agent in the treatment of AD.
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Affiliation(s)
- Zhuo Min
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Ying Tang
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Xiao-Tong Hu
- Department of Neurology, The Ninth People's Hospital of Chongqing, Chongqing, China
| | - Bing-Lin Zhu
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Yuan-Lin Ma
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Jing-Si Zha
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Xiao-Juan Deng
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Zhen Yan
- Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, NY, United States
| | - Guo-Jun Chen
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing, China
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21
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Santos M, Pereira PM, Varanda AS, Carvalho J, Azevedo M, Mateus DD, Mendes N, Oliveira P, Trindade F, Pinto MT, Bordeira-Carriço R, Carneiro F, Vitorino R, Oliveira C, Santos MAS. Codon misreading tRNAs promote tumor growth in mice. RNA Biol 2018; 15:773-786. [PMID: 29558247 DOI: 10.1080/15476286.2018.1454244] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Deregulation of tRNAs, aminoacyl-tRNA synthetases and tRNA modifying enzymes are common in cancer, raising the hypothesis that protein synthesis efficiency and accuracy (mistranslation) are compromised in tumors. We show here that human colon tumors and xenograft tumors produced in mice by two epithelial cancer cell lines mistranslate 2- to 4-fold more frequently than normal tissue. To clarify if protein mistranslation plays a role in tumor biology, we expressed mutant Ser-tRNAs that misincorporate Ser-at-Ala (frequent error) and Ser-at-Leu (infrequent error) in NIH3T3 cells and investigated how they responded to the proteome instability generated by the amino acid misincorporations. There was high tolerance to both misreading tRNAs, but the Ser-to-Ala misreading tRNA was a more potent inducer of cell transformation, stimulated angiogenesis and produced faster growing tumors in mice than the Ser-to-Leu misincorporating tRNA. Upregulation of the Akt pathway and the UPR were also observed. Most surprisingly, the relative expression of both misreading tRNAs increased during tumor growth, suggesting that protein mistranslation is advantageous in cancer contexts. These data highlight new features of protein synthesis deregulation in tumor biology.
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Affiliation(s)
- Mafalda Santos
- a Department of Medical Sciences and Institute of Biomedicine - iBiMED , University of Aveiro , Aveiro , Portugal.,b Expression Regulation in Cancer, Institute of Molecular Pathology and Immunology, University of Porto (IPATIMUP) , Porto , Portugal.,c Instituto de Investigação e Inovação em Saúde, University of Porto , Porto , Portugal
| | - Patricia M Pereira
- a Department of Medical Sciences and Institute of Biomedicine - iBiMED , University of Aveiro , Aveiro , Portugal.,b Expression Regulation in Cancer, Institute of Molecular Pathology and Immunology, University of Porto (IPATIMUP) , Porto , Portugal
| | - A Sofia Varanda
- a Department of Medical Sciences and Institute of Biomedicine - iBiMED , University of Aveiro , Aveiro , Portugal.,b Expression Regulation in Cancer, Institute of Molecular Pathology and Immunology, University of Porto (IPATIMUP) , Porto , Portugal.,c Instituto de Investigação e Inovação em Saúde, University of Porto , Porto , Portugal
| | - Joana Carvalho
- b Expression Regulation in Cancer, Institute of Molecular Pathology and Immunology, University of Porto (IPATIMUP) , Porto , Portugal.,c Instituto de Investigação e Inovação em Saúde, University of Porto , Porto , Portugal
| | - Mafalda Azevedo
- b Expression Regulation in Cancer, Institute of Molecular Pathology and Immunology, University of Porto (IPATIMUP) , Porto , Portugal
| | - Denisa D Mateus
- b Expression Regulation in Cancer, Institute of Molecular Pathology and Immunology, University of Porto (IPATIMUP) , Porto , Portugal
| | - Nuno Mendes
- b Expression Regulation in Cancer, Institute of Molecular Pathology and Immunology, University of Porto (IPATIMUP) , Porto , Portugal.,c Instituto de Investigação e Inovação em Saúde, University of Porto , Porto , Portugal
| | - Patricia Oliveira
- b Expression Regulation in Cancer, Institute of Molecular Pathology and Immunology, University of Porto (IPATIMUP) , Porto , Portugal.,c Instituto de Investigação e Inovação em Saúde, University of Porto , Porto , Portugal
| | - Fábio Trindade
- a Department of Medical Sciences and Institute of Biomedicine - iBiMED , University of Aveiro , Aveiro , Portugal.,d Department of Physiology and Cardiothoracic Surgery, Faculty of Medicine , University of Porto , Porto , Portugal
| | - Marta Teixeira Pinto
- b Expression Regulation in Cancer, Institute of Molecular Pathology and Immunology, University of Porto (IPATIMUP) , Porto , Portugal.,c Instituto de Investigação e Inovação em Saúde, University of Porto , Porto , Portugal
| | - Renata Bordeira-Carriço
- b Expression Regulation in Cancer, Institute of Molecular Pathology and Immunology, University of Porto (IPATIMUP) , Porto , Portugal.,c Instituto de Investigação e Inovação em Saúde, University of Porto , Porto , Portugal
| | - Fátima Carneiro
- b Expression Regulation in Cancer, Institute of Molecular Pathology and Immunology, University of Porto (IPATIMUP) , Porto , Portugal.,c Instituto de Investigação e Inovação em Saúde, University of Porto , Porto , Portugal.,e Dept. of Pathology, Faculty of Medicine , University of Porto , Porto , Portugal
| | - Rui Vitorino
- a Department of Medical Sciences and Institute of Biomedicine - iBiMED , University of Aveiro , Aveiro , Portugal
| | - Carla Oliveira
- b Expression Regulation in Cancer, Institute of Molecular Pathology and Immunology, University of Porto (IPATIMUP) , Porto , Portugal.,c Instituto de Investigação e Inovação em Saúde, University of Porto , Porto , Portugal.,e Dept. of Pathology, Faculty of Medicine , University of Porto , Porto , Portugal
| | - Manuel A S Santos
- a Department of Medical Sciences and Institute of Biomedicine - iBiMED , University of Aveiro , Aveiro , Portugal
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22
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Kasteri J, Das D, Zhong X, Persaud L, Francis A, Muharam H, Sauane M. Translation Control by p53. Cancers (Basel) 2018; 10:cancers10050133. [PMID: 29734756 PMCID: PMC5977106 DOI: 10.3390/cancers10050133] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 05/02/2018] [Accepted: 05/03/2018] [Indexed: 12/11/2022] Open
Abstract
The translation of mRNAs plays a critical role in the regulation of gene expression and therefore, in the regulation of cell proliferation, differentiation and apoptosis. Unrestricted initiation of translation causes malignant transformation and plays a key role in the maintenance and progression of cancers. Translation initiation is regulated by the ternary complex and the eukaryotic initiation factor 4F (eIF4F) complex. The p53 tumor suppressor protein is the most well studied mammalian transcription factor that mediates a variety of anti-proliferative processes. Post-transcriptional mechanisms of gene expression in general and those of translation in particular play a major role in shaping the protein composition of the cell. The p53 protein regulates transcription and controls eIF4F, the ternary complex and the synthesis of ribosomal components, including the down-regulation of rRNA genes. In summary, the induction of p53 regulates protein synthesis and translational control to inhibit cell growth.
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Affiliation(s)
- Justina Kasteri
- Department of Biological Sciences, Herbert H. Lehman College, City University of New York, 250 Bedford Park Boulevard West, Bronx, NY 10468, USA.
| | - Dibash Das
- Department of Biological Sciences, Herbert H. Lehman College, City University of New York, 250 Bedford Park Boulevard West, Bronx, NY 10468, USA.
- Department of Biology, The Graduate Center, City University of New York, 365 Fifth Avenue, Room, 250 Bedford Park Boulevard West, Bronx, NY 10468, USA.
| | - Xuelin Zhong
- Department of Biological Sciences, Herbert H. Lehman College, City University of New York, 250 Bedford Park Boulevard West, Bronx, NY 10468, USA.
- Department of Biology, The Graduate Center, City University of New York, 365 Fifth Avenue, Room, 250 Bedford Park Boulevard West, Bronx, NY 10468, USA.
| | - Leah Persaud
- Department of Biological Sciences, Herbert H. Lehman College, City University of New York, 250 Bedford Park Boulevard West, Bronx, NY 10468, USA.
- Department of Biology, The Graduate Center, City University of New York, 365 Fifth Avenue, Room, 250 Bedford Park Boulevard West, Bronx, NY 10468, USA.
| | - Ashleigh Francis
- Department of Biological Sciences, Herbert H. Lehman College, City University of New York, 250 Bedford Park Boulevard West, Bronx, NY 10468, USA.
| | - Hilal Muharam
- Department of Biological Sciences, Herbert H. Lehman College, City University of New York, 250 Bedford Park Boulevard West, Bronx, NY 10468, USA.
| | - Moira Sauane
- Department of Biological Sciences, Herbert H. Lehman College, City University of New York, 250 Bedford Park Boulevard West, Bronx, NY 10468, USA.
- Department of Biology, The Graduate Center, City University of New York, 365 Fifth Avenue, Room, 250 Bedford Park Boulevard West, Bronx, NY 10468, USA.
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23
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Xing Y, Ge Y, Liu C, Zhang X, Jiang J, Wei Y. ER stress inducer tunicamycin suppresses the self-renewal of glioma-initiating cell partly through inhibiting Sox2 translation. Oncotarget 2017; 7:36395-36406. [PMID: 27119230 PMCID: PMC5095008 DOI: 10.18632/oncotarget.8954] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 04/11/2016] [Indexed: 11/25/2022] Open
Abstract
Glioma-initiating cells possess tumor-initiating potential and are relatively resistant to conventional chemotherapy and irradiation. Therefore, their elimination is an essential factor for the development of efficient therapy. Here, we report that endoplasmic reticulum (ER) stress inducer tunicamycin inhibits glioma-initiating cell self-renewal as determined by neurosphere formation assay. Moreover, tunicamycin decreases the efficiency of glioma-initiating cell to initiate tumor formation. Although tunicamycin induces glioma-initiating cell apoptosis, apoptosis inhibitor z-VAD-fmk only partly abrogates the reduction in glioma-initiating cell self-renewal induced by tunicamycin. Indeed, tunicamycin reduces the expression of self-renewal regulator Sox2 at translation level. Overexpression of Sox2 obviously abrogates the reduction in glioma-initiating cell self-renewal induced by tunicamycin. Taken together, tunicamycin suppresses the self-renewal and tumorigenic potential of glioma-initiating cell partly through reducing Sox2 translation. This finding provides a cue to potential effective treatment of glioblastoma through controlling stem cells.
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Affiliation(s)
- Yang Xing
- Key Laboratory of Glycoconjuates Research, Ministry of Public Health, Department of Biochemistry and Molecular Biology, Shanghai Medical College of Fudan University, Shanghai, People's Republic of China
| | - Yuqing Ge
- Key Laboratory of Glycoconjuates Research, Ministry of Public Health, Department of Biochemistry and Molecular Biology, Shanghai Medical College of Fudan University, Shanghai, People's Republic of China
| | - Chanjuan Liu
- Key Laboratory of Glycoconjuates Research, Ministry of Public Health, Department of Biochemistry and Molecular Biology, Shanghai Medical College of Fudan University, Shanghai, People's Republic of China
| | - Xiaobiao Zhang
- Division of Neurosurgery, Zhongshan Hospital, Fudan University, Shanghai, People's Republic of China
| | - Jianhai Jiang
- Key Laboratory of Glycoconjuates Research, Ministry of Public Health, Department of Biochemistry and Molecular Biology, Shanghai Medical College of Fudan University, Shanghai, People's Republic of China
| | - Yuanyan Wei
- Key Laboratory of Glycoconjuates Research, Ministry of Public Health, Department of Biochemistry and Molecular Biology, Shanghai Medical College of Fudan University, Shanghai, People's Republic of China
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24
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Persaud L, Zhong X, Alvarado G, Do W, Dejoie J, Zybtseva A, Aktas BH, Sauane M. eIF2α Phosphorylation Mediates IL24-Induced Apoptosis through Inhibition of Translation. Mol Cancer Res 2017; 15:1117-1124. [PMID: 28461326 DOI: 10.1158/1541-7786.mcr-16-0454] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 04/01/2017] [Accepted: 04/26/2017] [Indexed: 11/16/2022]
Abstract
IL24 is an immunomodulatory cytokine that also displays broad cancer-specific suppressor effects. The tumor-suppressor activities of IL24 include inhibition of angiogenesis, sensitization to chemotherapy, and cancer-specific apoptosis. Supra-physiologic activation and/or overexpression of translation initiation factors are implicated in the initiation and progression of cancer animal models as well as a subset of human cancers. Activation and/or overexpression of translation initiation factors correlate with aggressiveness of cancer and poor prognosis. Two rate-limiting translation initiation complexes, the ternary complex and the eIF4F complex, are regulated by eIF2α and 4E-BP1 phosphorylation, respectively. The work reported here provides direct evidence that IL24 induces inhibition of translation initiation leading to apoptosis in squamous cell carcinoma. A dominant constitutively active mutant of eIF2α, which is resistant to phosphorylation, was used to determine the involvement of eIF2α in IL24-induced apoptosis. Treatment with IL24 resulted in inhibition of protein synthesis, expression of downstream biomarkers of ternary complex depletion such as CHOP, and induction of apoptosis in cancer cells. The constitutively active nonphosphorylatable mutant of eIF2α, eIF2α-S51A, reversed both the IL24-mediated translational block and IL24-induced apoptosis. Intriguingly, IL24 treatment also caused hypophosphorylation of 4E-BP1, which binds to eIF4E with high affinity, thus preventing its association with eIF4G and therefore preventing elF4F complex assembly.Implications: These results demonstrate a previously unrecognized role of IL24 in inhibition of translation, mediated through both phosphorylation of eIF2α and dephosphorylation of 4E-BP1, and provide the first direct evidence for translation control of gene-specific expression by IL24. Mol Cancer Res; 15(8); 1117-24. ©2017 AACR.
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Affiliation(s)
- Leah Persaud
- Department of Biological Sciences, Herbert H. Lehman College, City University of New York, Bronx, New York.,Department of Biology, the Graduate Center, City University of New York, New York, New York
| | - Xuelin Zhong
- Department of Biological Sciences, Herbert H. Lehman College, City University of New York, Bronx, New York.,Department of Biology, the Graduate Center, City University of New York, New York, New York
| | - Giselle Alvarado
- Department of Biological Sciences, Herbert H. Lehman College, City University of New York, Bronx, New York
| | - Winchie Do
- Department of Biological Sciences, Herbert H. Lehman College, City University of New York, Bronx, New York
| | - Jordan Dejoie
- Department of Biological Sciences, Herbert H. Lehman College, City University of New York, Bronx, New York
| | - Anna Zybtseva
- Department of Biological Sciences, Herbert H. Lehman College, City University of New York, Bronx, New York
| | - Bertal Huseyin Aktas
- Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts.,Harvard Medical School, Laboratory for Translational Research, Cambridge, Massachusetts
| | - Moira Sauane
- Department of Biological Sciences, Herbert H. Lehman College, City University of New York, Bronx, New York. .,Department of Biology, the Graduate Center, City University of New York, New York, New York
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25
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Kourtis N, Tavernarakis N. Protein Synthesis Rate Assessment by Fluorescence Recovery after Photobleaching (FRAP). Bio Protoc 2017; 7:e2156. [PMID: 28286807 DOI: 10.21769/bioprotoc.2156] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
Abstract
Currently available biochemical methods cannot be applied to monitor protein synthesis in specific cells or tissues, in live specimens. Here, we describe a non-invasive method for monitoring protein synthesis in single cells or tissues with intrinsically different translation rates, in live Caenorhabditis elegans animals.
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Affiliation(s)
- Nikos Kourtis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology Hellas, Crete, Greece; Department of Pathology, NYU School of Medicine, New York, USA
| | - Nektarios Tavernarakis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology Hellas, Crete, Greece; Department of Basic Sciences, Faculty of Medicine, University of Crete, Crete, Greece
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26
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Fischer PM. Approved and Experimental Small-Molecule Oncology Kinase Inhibitor Drugs: A Mid-2016 Overview. Med Res Rev 2016; 37:314-367. [DOI: 10.1002/med.21409] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Revised: 08/04/2016] [Accepted: 08/09/2016] [Indexed: 12/14/2022]
Affiliation(s)
- Peter M. Fischer
- School of Pharmacy and Centre for Biomolecular Sciences; University of Nottingham; Nottingham NG7 2RD UK
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27
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Genome-wide profiling of transfer RNAs and their role as novel prognostic markers for breast cancer. Sci Rep 2016; 6:32843. [PMID: 27604545 PMCID: PMC5015097 DOI: 10.1038/srep32843] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 08/11/2016] [Indexed: 11/25/2022] Open
Abstract
Transfer RNAs (tRNAs, key molecules in protein synthesis) have not been investigated as potential prognostic markers in breast cancer (BC), despite early findings of their dysregulation and diagnostic potential. We aim to comprehensively profile tRNAs from breast tissues and to evaluate their role as prognostic markers (Overall Survival, OS and Recurrence Free Survival, RFS). tRNAs were profiled from 11 normal breast and 104 breast tumor tissues using next generation sequencing. We adopted a Case-control (CC) and Case-Only (CO) association study designs. Risk scores constructed from tRNAs were subjected to univariate and multivariate Cox-proportional hazards regression to investigate their prognostic value. Of the 571 tRNAs profiled, 76 were differentially expressed (DE) and three were significant for OS in the CC approach. We identified an additional 11 tRNAs associated with OS and 14 tRNAs as significant for RFS in the CO approach, indicating that CC alone may not capture all discriminatory tRNAs in prognoses. In both the approaches, the risk scores were significant in the multivariate analysis as independent prognostic factors, and patients belonging to high-risk group were associated with poor prognosis. Our results confirmed global up-regulation of tRNAs in BC and identified tRNAs as potential novel prognostic markers for BC.
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28
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Nayak S, Siddiqui JK, Varner JD. Modelling and analysis of an ensemble of eukaryotic translation initiation models. IET Syst Biol 2016; 5:2. [PMID: 21261397 DOI: 10.1049/iet-syb.2009.0065] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Programmed protein synthesis plays an important role in the cell cycle. Deregulated translation has been observed in several cancers. In this study, the authors constructed an ensemble of mathematical models describing the integration of growth factor signals with translation initiation. Using these models, the authors estimated critical structural features of the translation architecture. Sensitivity and robustness analysis with and without growth factors suggested that a balance between competing regulatory programmes governed translation initiation. Proteins such as Akt and mTor promoted initiation by integrating growth factor signals with the assembly of the 80S initiation complex. However, negative regulators such as PTEN and 4EBP1 restrained initiation in the absence of stimulation. Other proteins such as eIF4E were also found to be structurally critical as deletion of amplification of these components resulted in a network incapable of nominal operation. These findings could help understand the molecular basis of translation deregulation observed in cancer and perhaps lead to new anti-cancer therapeutic strategies. [Includes supplementary material].
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Affiliation(s)
- S Nayak
- Cornell University, School of Chemical and Biomolecular Engineering, Ithaca, USA
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29
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Fischer P, Preiss A, Nagel AC. A triangular connection between Cyclin G, PP2A and Akt1 in the regulation of growth and metabolism in Drosophila. Fly (Austin) 2016; 10:11-8. [PMID: 26980713 PMCID: PMC4934794 DOI: 10.1080/19336934.2016.1162362] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Size and weight control is a tightly regulated process, involving the highly conserved Insulin receptor/target of rapamycin (InR/TOR) signaling cascade. We recently identified Cyclin G (CycG) as an important modulator of InR/TOR signaling activity in Drosophila. cycG mutant flies are underweight and show a disturbed fat metabolism resembling TOR mutants. In fact, InR/TOR signaling activity is disturbed in cycG mutants at the level of Akt1, the central kinase linking InR and TORC1. Akt1 is negatively regulated by protein phosphatase PP2A. Notably the binding of the PP2A B′-regulatory subunit Widerborst (Wdb) to Akt1 is differentially regulated in cycG mutants, presumably by a direct interaction of CycG and Wdb. Since the metabolic defects of cycG mutant animals are abrogated by a concomitant loss of Wdb, CycG presumably influences Akt1 activity at the PP2A nexus. Here we show that Well rounded (Wrd), another B' subunit of PP2A in Drosophila, binds CycG similar to Wdb, and that its loss ameliorates some, but not all, of the metabolic defects of cycG mutants. We propose a model, whereby the binding of CycG to a particular B′-regulatory subunit influences the tissue specific activity of PP2A, required for the fine tuning of the InR/TOR signaling cascade in Drosophila.
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Affiliation(s)
- Patrick Fischer
- a Institute of Genetics, University of Hohenheim , Stuttgart , Germany
| | - Anette Preiss
- a Institute of Genetics, University of Hohenheim , Stuttgart , Germany
| | - Anja C Nagel
- a Institute of Genetics, University of Hohenheim , Stuttgart , Germany
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30
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Marcus H, Attar-Schneider O, Dabbah M, Zismanov V, Tartakover-Matalon S, Lishner M, Drucker L. Mesenchymal stem cells secretomes' affect multiple myeloma translation initiation. Cell Signal 2016; 28:620-30. [PMID: 26976208 DOI: 10.1016/j.cellsig.2016.03.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 03/01/2016] [Accepted: 03/08/2016] [Indexed: 12/29/2022]
Abstract
Bone marrow mesenchymal stem cells' (BM-MSCs) role in multiple myeloma (MM) pathogenesis is recognized. Recently, we have published that co-culture of MM cell lines with BM-MSCs results in mutual modulation of phenotype and proteome (via translation initiation (TI) factors eIF4E/eIF4GI) and that there are differences between normal donor BM-MSCs (ND-MSCs) and MM BM-MSCs (MM-MSCs) in this crosstalk. Here, we aimed to assess the involvement of soluble BM-MSCs' (ND, MM) components, more easily targeted, in manipulation of MM cell lines phenotype and TI with specific focus on microvesicles (MVs) capable of transferring critical biological material. We applied ND and MM-MSCs 72h secretomes to MM cell lines (U266 and ARP-1) for 12-72h and then assayed the cells' (viability, cell count, cell death, proliferation, cell cycle, autophagy) and TI (factors: eIF4E, teIF4GI; regulators: mTOR, MNK1/2, 4EBP; targets: cyclin D1, NFκB, SMAD5, cMyc, HIF1α). Furthermore, we dissected the secretome into >100kDa and <100kDa fractions and repeated the experiments. Finally, MVs were isolated from the ND and MM-MSCs secretomes and applied to MM cell lines. Phenotype and TI were assessed. Secretomes of BM-MSCs (ND, MM) significantly stimulated MM cell lines' TI, autophagy and proliferation. The dissected secretome yielded different effects on MM cell lines phenotype and TI according to fraction (>100kDa- repressed; <100kDa- stimulated) but with no association to source (ND, MM). Finally, in analyses of MVs extracted from BM-MSCs (ND, MM) we witnessed differences in accordance with source: ND-MSCs MVs inhibited proliferation, autophagy and TI whereas MM-MSCs MVs stimulated them. These observations highlight the very complex communication between MM and BM-MSCs and underscore its significance to major processes in the malignant cells. Studies into the influential MVs cargo are underway and expected to uncover targetable signals in the regulation of the TI/proliferation/autophagy cascade.
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Affiliation(s)
- H Marcus
- Oncogenetic Laboratory, Tel Aviv University, Tel Aviv, Israel; Sackler faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - O Attar-Schneider
- Oncogenetic Laboratory, Tel Aviv University, Tel Aviv, Israel; Sackler faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - M Dabbah
- Oncogenetic Laboratory, Tel Aviv University, Tel Aviv, Israel; Sackler faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - V Zismanov
- Oncogenetic Laboratory, Tel Aviv University, Tel Aviv, Israel; Sackler faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - S Tartakover-Matalon
- Oncogenetic Laboratory, Tel Aviv University, Tel Aviv, Israel; Sackler faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - M Lishner
- Oncogenetic Laboratory, Tel Aviv University, Tel Aviv, Israel; Internal Medicine Department, Meir Medical Center, Kfar Saba, Tel Aviv University, Tel Aviv, Israel; Sackler faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - L Drucker
- Oncogenetic Laboratory, Tel Aviv University, Tel Aviv, Israel; Sackler faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
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31
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Koo J, Wang X, Owonikoko TK, Ramalingam SS, Khuri FR, Sun SY. GSK3 is required for rapalogs to induce degradation of some oncogenic proteins and to suppress cancer cell growth. Oncotarget 2016; 6:8974-87. [PMID: 25797247 PMCID: PMC4496196 DOI: 10.18632/oncotarget.3291] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 02/05/2015] [Indexed: 12/02/2022] Open
Abstract
The single-agent activity of rapalogs (rapamycin and its analogues) in most tumor types has been modest at best. The underlying mechanisms are largely unclear. In this report, we have uncovered a critical role of GSK3 in regulating degradation of some oncogenic proteins induced by rapalogs and cell sensitivity to rapalogs. The basal level of GSK3 activity was positively correlated with cell sensitivity of lung cancer cell lines to rapalogs. GSK3 inhibition antagonized rapamycin's growth inhibitory effects both in vitro and in vivo, while enforced activation of GSK3β sensitized cells to rapamycin. GSK3 inhibition rescued rapamcyin-induced reduction of several oncogenic proteins such as cyclin D1, Mcl-1 and c-Myc, without interfering with the ability of rapamycin to suppress mTORC1 signaling and cap binding. Interestingly, rapamycin induces proteasomal degradation of these oncogenic proteins, as evidenced by their decreased stabilities induced by rapamcyin and rescue of their reduction by proteasomal inhibition. Moreover, acute or short-time rapamycin treatment dissociated not only raptor, but also rictor from mTOR in several tested cell lines, suggesting inhibition of both mTORC1 and mTORC2. Thus, induction of GSK3-dependent degradation of these oncogenic proteins is likely secondary to mTORC2 inhibition; this effect should be critical for rapamycin to exert its anticancer activity.
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Affiliation(s)
- Junghui Koo
- Department of Hematology and Medical Oncology, Emory University School of Medicine and Winship Cancer Institute, Atlanta, GA, USA
| | - Xuerong Wang
- Department of Pharmacology, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Taofeek K Owonikoko
- Department of Hematology and Medical Oncology, Emory University School of Medicine and Winship Cancer Institute, Atlanta, GA, USA
| | - Suresh S Ramalingam
- Department of Hematology and Medical Oncology, Emory University School of Medicine and Winship Cancer Institute, Atlanta, GA, USA
| | - Fadlo R Khuri
- Department of Hematology and Medical Oncology, Emory University School of Medicine and Winship Cancer Institute, Atlanta, GA, USA
| | - Shi-Yong Sun
- Department of Hematology and Medical Oncology, Emory University School of Medicine and Winship Cancer Institute, Atlanta, GA, USA
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32
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Zhang P, Zhu X, Wu Y, Hu R, Li D, Du J, Jiao X, He X. Histone deacetylase inhibitors reduce WB-F344 oval cell viability and migration capability by suppressing AKT/mTOR signaling in vitro. Arch Biochem Biophys 2015; 590:1-9. [PMID: 26558695 DOI: 10.1016/j.abb.2015.11.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 11/03/2015] [Accepted: 11/04/2015] [Indexed: 12/12/2022]
Abstract
Histone deacetylase (HDAC) can blockDNA replication and transcription and altered HDAC expression was associated with tumorigenesis. This study investigated the effects of HDAC inhibitors on hepatic oval cells and aimed to delineate the underlying molecular events. Hepatic oval cells were treated with two different HDAC inhibitors, suberoylanilidehydroxamic acid (SAHA) and trichostatin-A (TSA). Cells were subjected to cell morphology, cell viability, cell cycle, and wound healing assays. The expression of proteins related to both apoptosis and the cell cycle, and proteins of the AKT/mammalian target of rapamycin (mTOR) signaling pathway were analyzed by Western blot. The data showed that HDAC inhibitors reduced oval cell viability and migration capability, and arrested oval cells at the G0/G1 and S phases of the cell cycle, in a dose- and time-dependent manner. HDAC inhibitors altered cell morphology and reduced oval cell viability, and downregulated the expression of PCNA, cyclinD1, c-Myc and Bmi1 proteins, while also suppressing AKT/mTOR and its downstream target activity. In conclusion, this study demonstrates that HDAC inhibitors affect oval cells by suppressing AKT/mTOR signaling.
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Affiliation(s)
- Peng Zhang
- Organ Transplant Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Xiaofeng Zhu
- Organ Transplant Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Ying Wu
- Department of Biostatistics, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Ronglin Hu
- Organ Transplant Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Dongming Li
- Department of Hepatobiliary Surgery, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Jun Du
- Department of Microbial and Biochemical Pharmacy, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Xingyuan Jiao
- Organ Transplant Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China.
| | - Xiaoshun He
- Organ Transplant Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China.
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33
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Zhang P, Guo Z, Wu Y, Hu R, Du J, He X, Jiao X, Zhu X. Histone Deacetylase Inhibitors Inhibit the Proliferation of Gallbladder Carcinoma Cells by Suppressing AKT/mTOR Signaling. PLoS One 2015; 10:e0136193. [PMID: 26287365 PMCID: PMC4542213 DOI: 10.1371/journal.pone.0136193] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 07/31/2015] [Indexed: 12/18/2022] Open
Abstract
Gallbladder carcinoma is an aggressive malignancy with high mortality mainly due to the limited potential for curative resection and its resistance to chemotherapeutic agents. Here, we show that the histone deacetylase inhibitors (HDACIs) trichostatin-A (TSA) and suberoylanilide hydroxamic acid (SAHA) reduce the proliferation and induce apoptosis of gallbladder carcinoma cells by suppressing the AKT/mammalian target of rapamycin (mTOR) signaling. Gallbladder carcinoma SGC-996 cells were treated with different concentrations of TSA and SAHA for different lengths of time. Cell proliferation and morphology were assessed with MTT assay and microscopy, respectively. Cell cycle distribution and cell apoptosis were analyzed with flow cytometry. Western blotting was used to detect the proteins related to apoptosis, cell cycle, and the AKT/mTOR signaling pathway. Our data showed that TSA and SAHA reduced SGC-996 cell viability and arrested cell cycle at the G1 phase in a dose- and time-dependent manner. TSA and SAHA promoted apoptosis of SGC-996 cells, down-regulated the expression of cyclin D1, c-Myc and Bmi1, and decreased the phosphorylation of AKT, mTOR p70S6K1, S6 and 4E-BP1. Additionally, the mTOR inhibitor rapamycin further reduced the cell viability of TSA- and SAHA-treated SGC-996 cells and the phosphorylation of mTOR, whereas the mTOR activator 1,2-dioctanoyl-sn-glycero-3-phosphate (C8-PA) exerted the opposite influence. Our results demonstrate that histone deacetylase inhibitors (HDACIs) suppress the proliferation of gallbladder carcinoma cell via inhibition of AKT/mTOR signaling. These findings offer a mechanistic rationale for the application of HDACIs in gallbladder carcinoma treatment.
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Affiliation(s)
- Peng Zhang
- Organ Transplant Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Zhiyong Guo
- Organ Transplant Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Ying Wu
- Department of Biostatistics, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Ronglin Hu
- Organ Transplant Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Jun Du
- Department of Microbial and Biochemical Pharmacy, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, China
| | - Xiaoshun He
- Organ Transplant Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Xingyuan Jiao
- Organ Transplant Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
- * E-mail: (XJ); (XZ)
| | - Xiaofeng Zhu
- Organ Transplant Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
- * E-mail: (XJ); (XZ)
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34
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Tsun ZY, Possemato R. Amino acid management in cancer. Semin Cell Dev Biol 2015; 43:22-32. [PMID: 26277542 PMCID: PMC4800996 DOI: 10.1016/j.semcdb.2015.08.002] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 07/21/2015] [Accepted: 08/09/2015] [Indexed: 12/30/2022]
Abstract
Amino acids have a dual role in cellular metabolism, as they are both the building blocks for protein synthesis and intermediate metabolites which fuel other biosynthetic reactions. Recent work has demonstrated that deregulation of both arms of amino acid management are common alterations seen in cancer. Among the most highly consumed nutrients by cancer cells are the amino acids glutamine and serine, and the biosynthetic pathways that metabolize them are required in various cancer subtypes and the object of current efforts to target cancer metabolism. Also altered in cancer are components of the machinery which sense amino acid sufficiency, nucleated by the mechanistic target of rapamycin (mTOR), a key regulator of cell growth via modulation of key processes including protein synthesis and autophagy. The precise ways in which altered amino acid management supports cellular transformation remain mostly elusive, and a fuller mechanistic understanding of these processes will be important for efforts to exploit such alterations for cancer therapy.
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Affiliation(s)
- Zhi-Yang Tsun
- Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, Department of Biology, Nine Cambridge Center, Cambridge, MA 02142, USA
| | - Richard Possemato
- Department of Pathology, New York University School of Medicine, New York, NY 10016, USA.
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35
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Gao B, Roux PP. Translational control by oncogenic signaling pathways. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1849:753-65. [PMID: 25477072 DOI: 10.1016/j.bbagrm.2014.11.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2014] [Revised: 11/17/2014] [Accepted: 11/19/2014] [Indexed: 01/04/2023]
Abstract
Messenger RNA (mRNA) translation is highly regulated in cells and plays an integral role in the overall process of gene expression. The initiation phase of translation is considered to be the most rate-limiting and is often targeted by oncogenic signaling pathways to promote global protein synthesis and the selective translation of tumor-promoting mRNAs. Translational control is a crucial component of cancer development as it allows cancer cells to adapt to the altered metabolism that is generally associated with the tumor state. The phosphoinositide 3-kinase (PI3K)/Akt and Ras/mitogen-activated protein kinase (MAPK) pathways are strongly implicated in cancer etiology, and they exert their biological effects by modulating both global and specific mRNA translation. In addition to having respective translational targets, these pathways also impinge on the mechanistic/mammalian target of rapamycin (mTOR), which acts as a critical signaling node linking nutrient sensing to the coordinated regulation of cellular metabolism. mTOR is best known as a central regulator of protein synthesis and has been implicated in an increasing number of pathological conditions, including cancer. In this article, we describe the current knowledge on the roles and regulation of mRNA translation by various oncogenic signaling pathways, as well as the relevance of these molecular mechanisms to human malignancies. This article is part of a Special Issue entitled: Translation and cancer.
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Affiliation(s)
- Beichen Gao
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Montréal, Québec, Canada
| | - Philippe P Roux
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Montréal, Québec, Canada; Department of Pathology and Cell Biology, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada.
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Koide H, Asai T, Kato H, Yonenaga N, Yokota M, Ando H, Dewa T, Nango M, Maeda N, Oku N. Susceptibility of PTEN-positive metastatic tumors to small interfering RNA targeting the mammalian target of rapamycin. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2014; 11:185-94. [PMID: 25240598 DOI: 10.1016/j.nano.2014.09.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 09/02/2014] [Accepted: 09/11/2014] [Indexed: 01/10/2023]
Abstract
PTEN-positive tumors are not susceptible to the treatment with rapamycin, an inhibitor of the mammalian target of rapamycin (mTOR). Here, we determined the susceptibility of PTEN-positive cells to small interfering RNA for mTOR (si-mTOR) by using a novel liposomal delivery system. We prepared dicetyl phosphate-tetraethylenepentamine-based polycation liposomes (TEPA-PCL) decorated with polyethylene glycol (PEG) grafting Ala-Pro-Arg-Pro-Gly (APRPG), a VRGFR-1-targeting peptide. APRPG-PEG-decorated TEPA-PCL carrying si-mTOR (APRPG-TEPA-PCL/si-mTOR) had an antiproliferative effect against B16F10 murine melanoma cells (PTEN-positive) and significantly inhibited both the proliferation and tube formation of mouse 2H-11 endothelial-like cells (PTEN-positive). APRPG-TEPA-PCL/si-mTOR treatment did not induce Akt phosphorylation (Ser473) in either B16F10 or 2H-11 cells although there was strong phosphorylation of Akt in response to rapamycin treatment. Intravenous injection of APRPG-TEPA-PCL/si-mTOR significantly suppressed the tumor growth compared with rapamycin treatment in mice bearing B16F10 melanoma. These findings suggest that APRPG-TEPA-PCL/si-mTOR is useful for the treatment of PTEN-positive tumors.
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Affiliation(s)
- Hiroyuki Koide
- Department of Medical Biochemistry, University of Shizuoka School of Pharmaceutical Sciences, Shizuoka, Shizuoka, Japan
| | - Tomohiro Asai
- Department of Medical Biochemistry, University of Shizuoka School of Pharmaceutical Sciences, Shizuoka, Shizuoka, Japan
| | - Hiroki Kato
- Department of Medical Biochemistry, University of Shizuoka School of Pharmaceutical Sciences, Shizuoka, Shizuoka, Japan
| | - Norihito Yonenaga
- Department of Medical Biochemistry, University of Shizuoka School of Pharmaceutical Sciences, Shizuoka, Shizuoka, Japan
| | - Masafumi Yokota
- Department of Medical Biochemistry, University of Shizuoka School of Pharmaceutical Sciences, Shizuoka, Shizuoka, Japan
| | - Hidenori Ando
- Department of Medical Biochemistry, University of Shizuoka School of Pharmaceutical Sciences, Shizuoka, Shizuoka, Japan
| | - Takehisa Dewa
- Materials Science and Engineering, Nagoya Institute of Technology, Nagoya, Aichi, Japan
| | - Mamoru Nango
- Materials Science and Engineering, Nagoya Institute of Technology, Nagoya, Aichi, Japan
| | | | - Naoto Oku
- Department of Medical Biochemistry, University of Shizuoka School of Pharmaceutical Sciences, Shizuoka, Shizuoka, Japan.
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J. D'Souza RC, Knittle AM, Nagaraj N, van Dinther M, Choudhary C, ten Dijke P, Mann M, Sharma K. Time-resolved dissection of early phosphoproteome and ensuing proteome changes in response to TGF-. Sci Signal 2014; 7:rs5. [DOI: 10.1126/scisignal.2004856] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Abstract
Translation initiation plays a critical role in the regulation of cell growth and tumorigenesis. We report here that inhibiting translation initiation through induction of eIF2α phosphorylation by small-molecular-weight compounds restricts the availability of the eIF2·GTP·Met-tRNAi ternary complex and abrogates the proliferation of cancer cells in vitro and tumor growth in vivo. Restricting the availability of the ternary complex preferentially down-regulates the expression of growth-promoting proteins and up-regulates the expression of ER stress response genes in cancer cells as well as in tumors excised from either animal models of human cancer or cancer patients. These findings provide the first direct evidence for translational control of gene-specific expression by small molecules in vivo and indicate that translation initiation factors are bona fide targets for development of mechanism-specific anti-cancer agents.
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Ma J, Han LZ, Liang H, Mi C, Shi H, Lee JJ, Jin X. Celastrol inhibits the HIF-1α pathway by inhibition of mTOR/p70S6K/eIF4E and ERK1/2 phosphorylation in human hepatoma cells. Oncol Rep 2014; 32:235-42. [PMID: 24859482 DOI: 10.3892/or.2014.3211] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Accepted: 05/06/2014] [Indexed: 11/06/2022] Open
Abstract
Hypoxia-inducible factor-1 (HIF-1) is the central mediator of cellular responses to low oxygen and vital to many aspects of cancer biology. In a search for HIF-1 inhibitors, we identified celastrol as an inhibitor of HIF-1 activation from Tripterygium wilfordii. In the present study, we demonstrated the effect of celastrol on HIF-1 activation. Celastrol showed a potent inhibitory activity against HIF-1 activation induced by hypoxia in various human cancer cell lines. This compound markedly decreased the hypoxia-induced accumulation of HIF-1α protein dose-dependently, whereas it did not affect the expressions of HIF-1β and topoisomerase-I (topo‑I). Furthermore, celastrol prevented hypoxia-induced expression of HIF-1 target genes for vascular endothelial growth factor (VEGF) and erythropoietin (EPO). Further analysis revealed that celastrol inhibited HIF-1α protein synthesis, without affecting the expression level of HIF-1α mRNA or degradation of HIF-1α protein. Markedly, we found that suppression of HIF-1α accumulation by celastrol correlated with strong dephosphorylation of mammalian target of rapamycin (mTOR) and its effectors, ribosomal protein S6 kinase (p70S6K) and eukaryotic initiation factor 4E (eIF4E) and extracellular signal-regulated kinase (ERK), pathways known to regulate HIF-1α expression at the translational level. In vivo studies further confirmed the inhibitory effect of celastrol on the expression of HIF-1α proteins, leading to a decreased growth of Hep3B cells in a xenograft tumor model. Our data suggested that celastrol is an effective inhibitor of HIF-1 and provide new perspectives into the mechanism of its anticancer activity.
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Affiliation(s)
- Juan Ma
- Key Laboratory of Natural Resources of Changbai Mountain and Functional Molecules, Ministry of Education, College of Pharmacy, Yanbian University, Yanji, Jilin 133002, P.R. China
| | - Li Zhuo Han
- Department of Pharmacy, Jilin Province People's Hospital, Changchun, Jilin 130021, P.R. China
| | - He Liang
- Key Laboratory of Natural Resources of Changbai Mountain and Functional Molecules, Ministry of Education, College of Pharmacy, Yanbian University, Yanji, Jilin 133002, P.R. China
| | - Chunliu Mi
- Molecular Cancer Research Center, Yanbian University, Yanji, Jilin 133002, P.R. China
| | - Hui Shi
- Molecular Cancer Research Center, Yanbian University, Yanji, Jilin 133002, P.R. China
| | - Jung Joon Lee
- Molecular Cancer Research Center, Yanbian University, Yanji, Jilin 133002, P.R. China
| | - Xuejun Jin
- Key Laboratory of Natural Resources of Changbai Mountain and Functional Molecules, Ministry of Education, College of Pharmacy, Yanbian University, Yanji, Jilin 133002, P.R. China
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Koo J, Yue P, Gal AA, Khuri FR, Sun SY. Maintaining glycogen synthase kinase-3 activity is critical for mTOR kinase inhibitors to inhibit cancer cell growth. Cancer Res 2014; 74:2555-68. [PMID: 24626091 DOI: 10.1158/0008-5472.can-13-2946] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
mTOR kinase inhibitors that target both mTORC1 and mTORC2 are being evaluated in cancer clinical trials. Here, we report that glycogen synthase kinase-3 (GSK3) is a critical determinant for the therapeutic response to this class of experimental drugs. Pharmacologic inhibition of GSK3 antagonized their suppressive effects on the growth of cancer cells similarly to genetic attenuation of GSK3. Conversely, expression of a constitutively activated form of GSK3β sensitized cancer cells to mTOR inhibition. Consistent with these findings, higher basal levels of GSK3 activity in a panel of human lung cancer cell lines correlated with more efficacious responses. Mechanistic investigations showed that mTOR kinase inhibitors reduced cyclin D1 levels in a GSK3β-dependent manner, independent of their effects on suppressing mTORC1 signaling and cap binding. Notably, selective inhibition of mTORC2 triggered proteasome-mediated cyclin D1 degradation, suggesting that mTORC2 blockade is responsible for GSK3-dependent reduction of cyclin D1. Silencing expression of the ubiquitin E3 ligase FBX4 rescued this reduction, implicating FBX4 in mediating this effect of mTOR inhibition. Together, our findings define a novel mechanism by which mTORC2 promotes cell growth, with potential implications for understanding the clinical action of mTOR kinase inhibitors.
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Affiliation(s)
- Junghui Koo
- Authors' Affiliations: Departments of Hematology and Medical Oncology and Pathology, Emory University School of Medicine and Winship Cancer Institute, Atlanta, Georgia
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Ilkow CS, Swift SL, Bell JC, Diallo JS. From scourge to cure: tumour-selective viral pathogenesis as a new strategy against cancer. PLoS Pathog 2014; 10:e1003836. [PMID: 24453963 PMCID: PMC3894191 DOI: 10.1371/journal.ppat.1003836] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Tumour mutations corrupt cellular pathways, and accumulate to disrupt, dysregulate, and ultimately avoid mechanisms of cellular control. Yet the very changes that tumour cells undergo to secure their own growth success also render them susceptible to viral infection. Enhanced availability of surface receptors, disruption of antiviral sensing, elevated metabolic activity, disengagement of cell cycle controls, hyperactivation of mitogenic pathways, and apoptotic avoidance all render the malignant cell environment highly supportive to viral replication. The therapeutic use of oncolytic viruses (OVs) with a natural tropism for infecting and subsequently lysing tumour cells is a rapidly progressing area of cancer research. While many OVs exhibit an inherent degree of tropism for transformed cells, this can be further promoted through pharmacological interventions and/or the introduction of viral mutations that generate recombinant oncolytic viruses adapted to successfully replicate only in a malignant cellular environment. Such adaptations that augment OV tumour selectivity are already improving the therapeutic outlook for cancer, and there remains tremendous untapped potential for further innovation.
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Affiliation(s)
- Carolina S. Ilkow
- Centre for Innovative Cancer Therapeutics, Ottawa Health Research Institute, Ottawa, Ontario, Canada
| | | | - John C. Bell
- Centre for Innovative Cancer Therapeutics, Ottawa Health Research Institute, Ottawa, Ontario, Canada
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
- * E-mail:
| | - Jean-Simon Diallo
- Centre for Innovative Cancer Therapeutics, Ottawa Health Research Institute, Ottawa, Ontario, Canada
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
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Larimer BM, Deutscher SL. Identification of a Peptide from In vivo Bacteriophage Display with Homology to EGFL6: A Candidate Tumor Vasculature Ligand in Breast Cancer. ACTA ACUST UNITED AC 2014; 5. [PMID: 26045973 PMCID: PMC4451856 DOI: 10.4172/2155-9929.1000178] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Background A crucial step in tumorigenesis is the recruitment of novel vasculature to the site of neoplasia. Currently, a number of high throughput techniques are employed to identify genes, mRNA and proteins that are aberrantly expressed in tumor vasculature. One drawback of such techniques is the lack of functional in vivo data that they provide. Bacteriophage (phage) display has been demonstrated in vivo to select peptides that home to tumors and tumor vasculature. The peptides can be compared to sequences of putative cancer-related proteins, in order to identify novel proteins essential for tumorigenesis. Objectives It was hypothesized that an in vivo selection for phage which targeted human breast cancer xenografts could identify peptides with homology to cancer-related proteins for in vivo imaging of breast cancer. Methods Following four rounds of in vivo selection in human MDA-MB-435 breast cancer xenografted mice, peptide 3-G03 was discovered with significant homology to a putative secreted protein termed EGFL6. Egfl6 mRNA is upregulated in several transcriptomic analyses of human cancer biopsies, and the protein may play a role in tumor vascularization. Results Egfl6 mRNA expression was demonstrated in MDA-MB-435 cells and EGFL6 protein was secreted from these cells. Based on homology of 3-G03 to EGFL6, an EGFL6 peptide was synthesized and shown to target MDA-MB-435 cells. EGFL6 peptide was radiolabeled with 111In and analyzed for biodistribution and tumor imaging capabilities. Single photon emission computed tomography imaging revealed uptake of the peptide in a manner consistent with other tumor vasculature targeting agents.
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Affiliation(s)
- Benjamin M Larimer
- Research Service, Harry S. Truman Veterans Memorial Hospital, Columbia, MO, USA ; Department of Biochemistry, University of Missouri, Columbia, MO, USA
| | - Susan L Deutscher
- Research Service, Harry S. Truman Veterans Memorial Hospital, Columbia, MO, USA ; Department of Biochemistry, University of Missouri, Columbia, MO, USA
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Kang S, Dong SM, Kim BR, Park MS, Trink B, Byun HJ, Rho SB. Thioridazine induces apoptosis by targeting the PI3K/Akt/mTOR pathway in cervical and endometrial cancer cells. Apoptosis 2013; 17:989-97. [PMID: 22460505 PMCID: PMC3413814 DOI: 10.1007/s10495-012-0717-2] [Citation(s) in RCA: 105] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Recently, thioridazine (10-[2-(1-methyl-2-piperidyl) ethyl]-2-methylthiophenothiazine), a well-known anti-psychotic agent was found to have anti-cancer activity in cancer cells. However, the molecular mechanism of the agent in cellular signal pathways has not been well defined. Thioridazine significantly increased early- and late-stage apoptotic fraction in cervical and endometrial cancer cells, suggesting that suppression of cell growth by thioridazine was due to the induction of apoptosis. Cell cycle analysis indicated thioridazine induced the down-regulation of cyclin D1, cyclin A and CDK4, and the induction of p21 and p27, a cyclin-dependent kinase inhibitor. Additionally, we compared the influence of thioridazine with cisplatin used as a control, and similar patterns between the two drugs were observed in cervical and endometrial cancer cell lines. Furthermore, as expected, thioridazine successfully inhibited phosphorylation of Akt, phosphorylation of 4E-BP1 and phosphorylation of p70S6K, which is one of the best characterized targets of the mTOR complex cascade. These results suggest that thioridazine effectively suppresses tumor growth activity by targeting the PI3K/Akt/mTOR/p70S6K signaling pathway.
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Affiliation(s)
- Sokbom Kang
- Research Institute, National Cancer Center, 323, Ilsan-ro, Ilsandong-gu, Goyang-si, Gyeonggi-do 410-769 Republic of Korea
- Division of Gynecologic Cancer Research, Research Institute and Hospital, National Cancer Center, 323, Ilsan-ro, Ilsandong-gu, Goyang-si, Gyeonggi-do 410-769 Republic of Korea
| | - Seung Myung Dong
- Research Institute, National Cancer Center, 323, Ilsan-ro, Ilsandong-gu, Goyang-si, Gyeonggi-do 410-769 Republic of Korea
| | - Boh-Ram Kim
- Research Institute, National Cancer Center, 323, Ilsan-ro, Ilsandong-gu, Goyang-si, Gyeonggi-do 410-769 Republic of Korea
| | - Mi Sun Park
- Research Institute, National Cancer Center, 323, Ilsan-ro, Ilsandong-gu, Goyang-si, Gyeonggi-do 410-769 Republic of Korea
| | - Barry Trink
- Division of Head and Neck Cancer Research, Department of Otolaryngology and Head & Neck Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD 21231 USA
| | - Hyun-Jung Byun
- Research Institute, National Cancer Center, 323, Ilsan-ro, Ilsandong-gu, Goyang-si, Gyeonggi-do 410-769 Republic of Korea
| | - Seung Bae Rho
- Research Institute, National Cancer Center, 323, Ilsan-ro, Ilsandong-gu, Goyang-si, Gyeonggi-do 410-769 Republic of Korea
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Du W, Yi Y, Zhang H, Bergholz J, Wu J, Ying H, Zhang Y, Xiao ZXJ. Rapamycin inhibits IGF-1-mediated up-regulation of MDM2 and sensitizes cancer cells to chemotherapy. PLoS One 2013; 8:e63179. [PMID: 23638184 PMCID: PMC3640086 DOI: 10.1371/journal.pone.0063179] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Accepted: 03/29/2013] [Indexed: 11/19/2022] Open
Abstract
The Murine Double Minute 2 (MDM2) protein is a key regulator of cell proliferation and apoptosis that acts primarily by inhibiting the p53 tumor suppressor. Similarly, the PI3-Kinase (PI3K)/AKT pathway is critical for growth factor-mediated cell survival. Additionally, it has been reported that AKT can directly phosphorylate and activate MDM2. In this study, we show that IGF-1 up-regulates MDM2 protein levels in a PI3K/AKT-dependent manner. Inhibition of mTOR by rapamycin or expression of a dominant negative eukaryotic initiation factor 4E binding protein 1 (4EBP1) mutant protein, as well as ablation of eukaryotic initiation factor 4E (eIF4E), efficiently abolishes IGF-1-mediated up-regulation of MDM2. In addition, we show that rapamycin effectively inhibits MDM2 expression and sensitizes cancer cells to chemotherapy. Taken together, this study reveals a novel mechanism by which IGF-1 activates MDM2 via the mTOR pathway, and that pharmacologic inhibition of mTOR combined with chemotherapy may be more effective in treatment of a subset of cancers harboring increased MDM2 activation.
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Affiliation(s)
- Wei Du
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Yong Yi
- Center of Growth, Metabolism and Aging, College of Life Sciences and State Key Laboratory of Biotherapy, Sichuan University, Chengdu, China
| | - Haibo Zhang
- Center of Growth, Metabolism and Aging, College of Life Sciences and State Key Laboratory of Biotherapy, Sichuan University, Chengdu, China
| | - Johann Bergholz
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America
- Center of Growth, Metabolism and Aging, College of Life Sciences and State Key Laboratory of Biotherapy, Sichuan University, Chengdu, China
| | - Junfeng Wu
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Haoqiang Ying
- The University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America
| | - Yujun Zhang
- Center of Growth, Metabolism and Aging, College of Life Sciences and State Key Laboratory of Biotherapy, Sichuan University, Chengdu, China
| | - Zhi-Xiong Jim Xiao
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America
- Center of Growth, Metabolism and Aging, College of Life Sciences and State Key Laboratory of Biotherapy, Sichuan University, Chengdu, China
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Pavon-Eternod M, Gomes S, Rosner MR, Pan T. Overexpression of initiator methionine tRNA leads to global reprogramming of tRNA expression and increased proliferation in human epithelial cells. RNA (NEW YORK, N.Y.) 2013; 19:461-6. [PMID: 23431330 PMCID: PMC3677255 DOI: 10.1261/rna.037507.112] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Transfer RNAs (tRNAs) are typically considered housekeeping products with little regulatory function. However, several studies over the past 10 years have linked tRNA misregulation to cancer. We have previously reported that tRNA levels are significantly elevated in breast cancer and multiple myeloma cells. To further investigate the cellular and physiological effects of tRNA overexpression, we overexpressed tRNAi(Met) in two human breast epithelial cell lines. We then determined tRNA abundance changes and performed phenotypic characterization. Overexpression of tRNAi(Met) significantly altered the global tRNA expression profile and resulted in increased cell metabolic activity and cell proliferation. Our results extend the relevance of tRNA overexpression in human cells and underscore the complexity of cellular regulation of tRNA expression.
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Affiliation(s)
- Mariana Pavon-Eternod
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois 60637, USA
| | - Suzana Gomes
- Ben May Department of Cancer Research, University of Chicago, Chicago, Illinois 60637, USA
| | - Marsha R. Rosner
- Ben May Department of Cancer Research, University of Chicago, Chicago, Illinois 60637, USA
- Corresponding authorsE-mail E-mail
| | - Tao Pan
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois 60637, USA
- Corresponding authorsE-mail E-mail
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Rho SB, Byun HJ, Kim BR, Kim IS, Lee JH, Yoo R, Park ST, Park SH. GABAA receptor-binding protein promotes sensitivity to apoptosis induced by chemotherapeutic agents. Int J Oncol 2013; 42:1807-14. [PMID: 23545901 DOI: 10.3892/ijo.2013.1866] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 03/08/2013] [Indexed: 11/06/2022] Open
Abstract
In the present study, the expression of human γ-aminobutyrate type A (GABAA) receptor-binding protein (GABARBP) is downregulated in ovarian cancer cell lines and tissues. We also found that the specific function of GABAPBP was that of a novel pro-apoptotic protein. Both GABARBP and cisplatin suppressed cancer cell proliferation in a concentration-dependent manner. The combined treatment of GABARBP and cisplatin was more effective in inhibiting cell growth, as well as cell migration, than with either drug treatment alone. At the same time, the treatment combination is correlated with the downregulation of cyclin D1 and CDK4, arrested cell cycle progression in the G₀-G₁ phase and enhancing p53 expression, while also reducing Bcl-2 and Bcl-xL expression. The p53 and p21 promoter luciferase activities were induced by GABARBP, whereas there was no effect on the p53-/- and p21-/- system. In addition, p53 activity was validated with UV irradiation and siGABARBP. Taken together, our results indicate that GABARBP can regulate the pro-apoptotic activity of cisplatin via the upregulation of p53 expression.
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Affiliation(s)
- Seung Bae Rho
- Research Institute, National Cancer Center, Goyang-si, Gyeonggi-do 410-769, Republic of Korea.
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Wolf A, Rietscher K, Glaß M, Hüttelmaier S, Schutkowski M, Ihling C, Sinz A, Wingenfeld A, Mun A, Hatzfeld M. Insulin signaling via Akt2 switches plakophilin 1 function from stabilizing cell adhesion to promoting cell proliferation. J Cell Sci 2013; 126:1832-44. [PMID: 23444369 DOI: 10.1242/jcs.118992] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Downregulation of adherens junction proteins is a frequent event in carcinogenesis. How desmosomal proteins contribute to tumor formation by regulating the balance between adhesion and proliferation is not well understood. The desmosomal protein plakophilin 1 can increase intercellular adhesion by recruiting desmosomal proteins to the plasma membrane or stimulate proliferation by enhancing translation rates. Here, we show that these dual functions of plakophilin 1 are regulated by growth factor signaling. Insulin stimulation induced the phosphorylation of plakophilin 1, which correlated with reduced intercellular adhesion and an increased activity of plakophilin 1 in the stimulation of translation. Phosphorylation was mediated by Akt2 at four motifs within the plakophilin 1 N-terminal domain. A plakophilin 1 phospho-mimetic mutant revealed reduced intercellular adhesion and accumulated in the cytoplasm, where it increased translation and proliferation rates and conferred the capacity of anchorage-independent growth. The cytoplasmic accumulation was mediated by the stabilization of phosphorylated plakophilin 1, which displayed a considerably increased half-life, whereas non-phosphorylated plakophilin 1 was more rapidly degraded. Our data indicate that upon activation of growth factor signaling, plakophilin 1 switches from a desmosome-associated growth-inhibiting to a cytoplasmic proliferation-promoting function. This supports the view that the deregulation of plakophilin 1, as observed in several tumors, directly contributes to hyperproliferation and carcinogenesis in a context-dependent manner.
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Affiliation(s)
- Annika Wolf
- Institute of Molecular Medicine, Division of Pathobiochemistry, Martin-Luther-University Halle-Wittenberg, 06114 Halle, Germany
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Abstract
INTRODUCTION There has been a strong preclinical rationale for studying mammalian target of rapamycin (mTOR) inhibitors as single agents or in combination, in multiple malignancies and colorectal cancer in particular. AREAS COVERED The authors summarize the complete clinical experience to date of all trials, both published and in abstract form, of everolimus in colorectal cancer. While initial Phase I trials showed promise, further studies have confirmed that single agent everolimus is not active in advanced metastatic colorectal carcinoma with trials showing single agent tolerability, but without significant hints of efficacy in terms of either objective tumor responses or prolonged stable disease. Combination regimens, including combinations with cytotoxic chemotherapy, and inhibitors of VEGF, EGFR and HDAC have been tested specifically in the colorectal setting in Phase I and Phase II clinical trials. The authors discuss the potential reasons for mixed results and suggest future directions for the development of everolimus in colorectal malignancies. EXPERT OPINION Studies demonstrate limited clinical activity of everolimus for the treatment of advanced colorectal cancer and have been complicated by increases in toxicity. However, the central role of the PI3K/mTOR pathway in cancer biology suggests that other drug combinations with mTOR inhibition may still merit evaluation.
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Affiliation(s)
- Ivy Altomare
- Duke University Medical Center, Division of Medical Oncology, 3100 Tower Blvd Ste 600, Durham, NC 27707, USA.
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