51
|
Zhuo C, Fürstner A. Concise Synthesis of a Pateamine A Analogue with In Vivo Anticancer Activity Based on an Iron‐Catalyzed Pyrone Ring Opening/Cross‐Coupling. Angew Chem Int Ed Engl 2016; 55:6051-6. [DOI: 10.1002/anie.201602125] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Indexed: 11/07/2022]
Affiliation(s)
- Chun‐Xiang Zhuo
- Max-Planck-Institut für Kohlenforschung 45470 Mülheim/Ruhr Germany
| | - Alois Fürstner
- Max-Planck-Institut für Kohlenforschung 45470 Mülheim/Ruhr Germany
| |
Collapse
|
52
|
Popa A, Lebrigand K, Barbry P, Waldmann R. Pateamine A-sensitive ribosome profiling reveals the scope of translation in mouse embryonic stem cells. BMC Genomics 2016; 17:52. [PMID: 26764022 PMCID: PMC4712605 DOI: 10.1186/s12864-016-2384-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 01/06/2016] [Indexed: 01/02/2023] Open
Abstract
Background Open reading frames are common in long noncoding RNAs (lncRNAs) and 5’UTRs of protein coding transcripts (uORFs). The question of whether those ORFs are translated was recently addressed by several groups using ribosome profiling. Most of those studies concluded that certain lncRNAs and uORFs are translated, essentially based on computational analysis of ribosome footprints. However, major discrepancies remain on the scope of translation and the translational status of individual ORFs. In consequence, further criteria are required to reliably identify translated ORFs from ribosome profiling data. Results We examined the effect of the translation inhibitors pateamine A, harringtonine and puromycin on murine ES cell ribosome footprints. We found that pateamine A, a drug that targets eIF4A, allows a far more accurate identification of translated sequences than previously used drugs and computational scoring schemes. Our data show that at least one third but less than two thirds of ES cell lncRNAs are translated. We also identified translated uORFs in hundreds of annotated coding transcripts including key pluripotency transcripts, such as dicer, lin28, trim71, and ctcf. Conclusion Pateamine A inhibition data clearly increase the precision of the detection of translated ORFs in ribosome profiling experiments. Our data show that translation of lncRNAs and uORFs in murine ES cells is rather common although less pervasive than previously suggested. The observation of translated uORFs in several key pluripotency transcripts suggests that translational regulation by uORFs might be part of the network that defines mammalian stem cell identity. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2384-0) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Alexandra Popa
- Institut de Pharmacologie Moléculaire et Cellulaire (IPMC), University Nice Sophia Antipolis, CNRS, F06560, Sophia-Antipolis, France
| | - Kevin Lebrigand
- Institut de Pharmacologie Moléculaire et Cellulaire (IPMC), University Nice Sophia Antipolis, CNRS, F06560, Sophia-Antipolis, France
| | - Pascal Barbry
- Institut de Pharmacologie Moléculaire et Cellulaire (IPMC), University Nice Sophia Antipolis, CNRS, F06560, Sophia-Antipolis, France.
| | - Rainer Waldmann
- Institut de Pharmacologie Moléculaire et Cellulaire (IPMC), University Nice Sophia Antipolis, CNRS, F06560, Sophia-Antipolis, France
| |
Collapse
|
53
|
Ziehr B, Lenarcic E, Cecil C, Moorman NJ. The eIF4AIII RNA helicase is a critical determinant of human cytomegalovirus replication. Virology 2016; 489:194-201. [PMID: 26773380 DOI: 10.1016/j.virol.2015.12.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 12/18/2015] [Accepted: 12/19/2015] [Indexed: 01/08/2023]
Abstract
Human cytomegalovirus (HCMV) was recently shown to encode a large number of spliced mRNAs. While the nuclear export of unspliced viral transcripts has been extensively studied, the role of host mRNA export factors in HCMV mRNA trafficking remains poorly defined. We found that the eIF4AIII RNA helicase, a component of the exon junction complex, was necessary for efficient virus replication. Depletion of eIF4AIII limited viral DNA accumulation, export of viral mRNAs from the nucleus, and the production of progeny virus. However eIF4AIII was dispensable for the association of viral transcripts with ribosomes. We found that pateamine A, a natural compound that inhibits both eIF4AI/II and eIF4AIII, has potent antiviral activity and inhibits HCMV replication throughout the virus lytic cycle. Our results demonstrate that eIF4AIII is required for efficient HCMV replication, and suggest that eIF4A family helicases may be a new class of targets for the development of host-directed antiviral therapeutics.
Collapse
Affiliation(s)
- Ben Ziehr
- Department of Microbiology & Immunology, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Erik Lenarcic
- Department of Microbiology & Immunology, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Chad Cecil
- Department of Microbiology & Immunology, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Nathaniel J Moorman
- Department of Microbiology & Immunology, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
| |
Collapse
|
54
|
A phase I combination dose-escalation study of eribulin mesylate and gemcitabine in patients with advanced solid tumours: a study of the Princess Margaret Consortium. Br J Cancer 2015; 113:1534-40. [PMID: 26554651 PMCID: PMC4705880 DOI: 10.1038/bjc.2015.343] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 08/03/2015] [Accepted: 08/24/2015] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND Eribulin mesylate is a synthetic microtubule inhibitor that showed cytotoxic synergy in combination with gemcitabine preclinically. This combination was assessed in a Phase I dose-finding trial in patients diagnosed with advanced solid tumours who had received up to two prior chemotherapy regimens for metastatic disease (CP cohort). METHODS Dose escalation was performed in a 3+3 design to identify the recommended phase II dose (RP2D). Two additional expansion cohorts in women with gynaecologic cancers at the RP2D (G), and further dose escalation of metastatic chemotherapy-naive patients (CN), were evaluated. RESULTS 45 patients were treated: 21 (CP), 10 (G) and 14 (CN). The initial combination of eribulin and gemcitabine was administered on days 1, 8, and 15 of a 28-day cycle; however, due to 2 out of 6 dose-limiting haematological toxicities at the first dose level, a reduced dose-intense schedule was assessed. The RP2D was defined at 1.0 mg m(-2) eribulin and 1000 mg m(-2) gemcitabine day 1 and 8 q3 weeks. No other significant toxicities were observed in the G expansion cohort. Neutropenia prevented further dose escalation in the CN cohort. Objective responses were seen in all three cohorts - 2/21 (CP), 1/10 (G) and 2/14 (CN). CONCLUSIONS The combination of eribulin and gemcitabine was well tolerated at the RP2D.
Collapse
|
55
|
Kardos GR, Robertson GP. Therapeutic interventions to disrupt the protein synthetic machinery in melanoma. Pigment Cell Melanoma Res 2015; 28:501-19. [PMID: 26139519 PMCID: PMC4716672 DOI: 10.1111/pcmr.12391] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 06/30/2015] [Indexed: 01/23/2023]
Abstract
Control of the protein synthetic machinery is deregulated in many cancers, including melanoma, to increase the protein production. Tumor suppressors and oncogenes play key roles in protein synthesis from the transcription of rRNA and ribosome biogenesis to mRNA translation initiation and protein synthesis. Major signaling pathways are altered in melanoma to modulate the protein synthetic machinery, thereby promoting tumor development. However, despite the importance of this process in melanoma development, involvement of the protein synthetic machinery in this cancer type is an underdeveloped area of study. Here, we review the coupling of melanoma development to deregulation of the protein synthetic machinery. We examine existing knowledge regarding RNA polymerase I inhibition and mRNA translation focusing on their inhibition for therapeutic applications in melanoma. Furthermore, the contribution of amino acid biosynthesis and involvement of ribosomal proteins are also reviewed as future therapeutic strategies to target deregulated protein production in melanoma.
Collapse
Affiliation(s)
- Gregory R. Kardos
- Department of Pharmacology, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA, USA, 17033
- The Melanoma and Skin Cancer Center, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA, USA, 17033
- The Melanoma Therapeutics Program, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA, USA, 17033
| | - Gavin P. Robertson
- Department of Pharmacology, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA, USA, 17033
- Department of Pathology, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA, USA, 17033
- Department of Dermatology, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA, USA, 17033
- Department of Surgery, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA, USA, 17033
- The Melanoma and Skin Cancer Center, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA, USA, 17033
- The Melanoma Therapeutics Program, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA, USA, 17033
| |
Collapse
|
56
|
De Lerma Barbaro A. The complex liaison between cachexia and tumor burden (Review). Oncol Rep 2015; 34:1635-49. [PMID: 26239384 DOI: 10.3892/or.2015.4164] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 06/22/2015] [Indexed: 11/06/2022] Open
Abstract
Cachexia is a wasting syndrome that afflicts end-stage cancer patients. Whereas a consensus statement for a definition of cachexia recently has been accomplished, a useful measurement for this condition at present is lacking. The aim of the present review is to discuss the advantage of introducing the measurement of tumor burden for a better overall evaluation of cachexia. Our suggestion ensues from a somewhat novel perspective in the field of infectious disease research where a careful measurement of the pathogen load, between i.e. different host genotypes, leads to the definition of the concept of tolerance to the infectious insult. Indeed tolerance concurs, together the more classical resistance, in maintaining the host reproductive fitness or health state. Noticeably a similar reasoning may apply to tumor biology as well. Whereas the extent of cachexia increases with tumor burden, the relationship between these two correlates of tumor progression fluctuates in a broad range. We have selected from the literature studies in the rodent model where significant variation in the course of the wasting illness during cancer was observed and quantitatively assessed comparing experimental groups marked by different genotype, drug treatment, diet or gender. These studies may be further classified in two categories: the former where the experimental condition associated to milder cachexia is accompanied to a lesser tumor burden, the latter where the inhibition of cachexia results disentangled from the tumor burden, that is the whole number of cancer cells results unchanged or even, paradoxically, is increased. In addition we survey, even in the context of human malignancy, the significance and feasibility of plotting quantitative estimates of cachexia against the whole tumor burden. Ultimately, the principal endeavor of introducing the measurement of tumor burden, in both experimental and clinical oncology, may be to achieve a better assessment of the inter-individual variation in the host vulnerability to cancer cachexia.
Collapse
Affiliation(s)
- Andrea De Lerma Barbaro
- Biomedical Research Division, Department of Theoretical and Applied Sciences, University of Insubria, Busto Arsizio, Varese, Italy
| |
Collapse
|
57
|
Targeting the eIF4A RNA helicase as an anti-neoplastic approach. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2015; 1849:781-91. [DOI: 10.1016/j.bbagrm.2014.09.006] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 09/03/2014] [Indexed: 01/22/2023]
|
58
|
Pelletier J, Graff J, Ruggero D, Sonenberg N. Targeting the eIF4F translation initiation complex: a critical nexus for cancer development. Cancer Res 2015; 75:250-63. [PMID: 25593033 DOI: 10.1158/0008-5472.can-14-2789] [Citation(s) in RCA: 267] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Elevated protein synthesis is an important feature of many cancer cells and often arises as a consequence of increased signaling flux channeled to eukaryotic initiation factor 4F (eIF4F), the key regulator of the mRNA-ribosome recruitment phase of translation initiation. In many cellular and preclinical models of cancer, eIF4F deregulation results in changes in translational efficiency of specific mRNA classes. Importantly, many of these mRNAs code for proteins that potently regulate critical cellular processes, such as cell growth and proliferation, enhanced cell survival and cell migration that ultimately impinge on several hallmarks of cancer, including increased angiogenesis, deregulated growth control, enhanced cellular survival, epithelial-to-mesenchymal transition, invasion, and metastasis. By being positioned as the molecular nexus downstream of key oncogenic signaling pathways (e.g., Ras, PI3K/AKT/TOR, and MYC), eIF4F serves as a direct link between important steps in cancer development and translation initiation. Identification of mRNAs particularly responsive to elevated eIF4F activity that typifies tumorigenesis underscores the critical role of eIF4F in cancer and raises the exciting possibility of developing new-in-class small molecules targeting translation initiation as antineoplastic agents.
Collapse
Affiliation(s)
- Jerry Pelletier
- Department of Biochemistry, McGill University, Montreal, Québec, Canada. The Rosalind and Morris Goodman Cancer Research Center, McGill University, Montreal, Québec, Canada. Department of Oncology, McGill University, Montreal, Québec, Canada.
| | - Jeremy Graff
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana
| | - Davide Ruggero
- School of Medicine and Department of Urology, Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, California
| | - Nahum Sonenberg
- Department of Biochemistry, McGill University, Montreal, Québec, Canada. The Rosalind and Morris Goodman Cancer Research Center, McGill University, Montreal, Québec, Canada
| |
Collapse
|
59
|
Abstract
Dysregulation of mRNA translation is a frequent feature of neoplasia. Many oncogenes and tumour suppressors affect the translation machinery, making aberrant translation a widespread characteristic of tumour cells, independent of the genetic make-up of the cancer. Therefore, therapeutic agents that target components of the protein synthesis apparatus hold promise as novel anticancer drugs that can overcome intra-tumour heterogeneity. In this Review, we discuss the role of translation in cancer, with a particular focus on the eIF4F (eukaryotic translation initiation factor 4F) complex, and provide an overview of recent efforts aiming to 'translate' these results to the clinic.
Collapse
|
60
|
Sakiyama T, Tsurutani J, Iwasa T, Kawakami H, Nonagase Y, Yoshida T, Tanaka K, Fujisaka Y, Kurata T, Komoike Y, Nishio K, Nakagawa K. A phase I dose-escalation study of eribulin and S-1 for metastatic breast cancer. Br J Cancer 2015; 112:819-24. [PMID: 25654665 PMCID: PMC4453950 DOI: 10.1038/bjc.2015.10] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 12/12/2014] [Accepted: 12/21/2014] [Indexed: 02/07/2023] Open
Abstract
Background: We evaluated the safety, maximum-tolerated dose (MTD), pharmacokinetics, recommended dose for phase II (P2RD), and preliminary anticancer activity of a combination eribulin and S-1 therapeutic in metastatic breast cancer patients pretreated with anthracycline and taxane. Method: Patients aged 20–74 years were recruited. In level 1, patients received S-1 (65 mg m−2) from day 1 to 14, and eribulin (1.1 mg m−2) on day 1 and 8 in a 21-day cycle. In level 2, eribulin was increased to 1.4 mg m−2. In level 3, S-1 was increased to 80 mg m−2. Results: Twelve patients were enrolled into three cohorts. Planned dose escalation was completed, with one case exhibiting dose-limiting toxicity (grade 3 hypokalaemia) at level 3, without reaching the MTD. The P2RD was determined to be level 2 (eribulin 1.4 mg m−2 and S-1 65 mg m−2). The most common grade 3 or 4 toxicity was neutropenia (83.3%), followed by febrile neutropenia (25.0%). Five of eleven patients (41.7%) with measurable disease had a partial response. Pharmacokinetics were characterised by dose-dependent elimination and nonlinear exposure. Conclusion: Dose level 3 was not tolerated owing to febrile neutropenia development. Thus, intermediate dose level 2 was recommended for further evaluation. Preliminary antitumour activity warrants further investigation in this setting.
Collapse
Affiliation(s)
- T Sakiyama
- Department of Medical Oncology, Kindai University Faculty of Medicine, 377-2 Ohnohigashi, Osaka-sayama 589-8511, Japan
| | - J Tsurutani
- Department of Medical Oncology, Kindai University Faculty of Medicine, 377-2 Ohnohigashi, Osaka-sayama 589-8511, Japan
| | - T Iwasa
- Department of Medical Oncology, Kindai University Faculty of Medicine, 377-2 Ohnohigashi, Osaka-sayama 589-8511, Japan
| | - H Kawakami
- Department of Medical Oncology, Kindai University Faculty of Medicine, 377-2 Ohnohigashi, Osaka-sayama 589-8511, Japan
| | - Y Nonagase
- Department of Medical Oncology, Kindai University Faculty of Medicine, 377-2 Ohnohigashi, Osaka-sayama 589-8511, Japan
| | - T Yoshida
- Department of Medical Oncology, Kindai University Faculty of Medicine, 377-2 Ohnohigashi, Osaka-sayama 589-8511, Japan
| | - K Tanaka
- Department of Medical Oncology, Kindai University Faculty of Medicine, 377-2 Ohnohigashi, Osaka-sayama 589-8511, Japan
| | - Y Fujisaka
- Clinical Research Center, Osaka Medical Collage Hospital, 2-7 Daigaku-cho, Takatsuki 569-8686, Japan
| | - T Kurata
- Department of Thoracic Oncology, Kansai Medical University Hirakata Hospital, 2-3-1 Shinmachi, Hirakata 573-1191, Japan
| | - Y Komoike
- Department of Surgery, Kindai University Faculty of Medicine, 377-2 Ohnohigashi, Osaka-sayama 589-8511, Japan
| | - K Nishio
- Department of Genome Biology, Kindai University Faculty of Medicine, 377-2 Ohnohigashi, Osaka-sayama 589-8511, Japan
| | - K Nakagawa
- Department of Medical Oncology, Kindai University Faculty of Medicine, 377-2 Ohnohigashi, Osaka-sayama 589-8511, Japan
| |
Collapse
|
61
|
Anderson P, Kedersha N, Ivanov P. Stress granules, P-bodies and cancer. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1849:861-70. [PMID: 25482014 DOI: 10.1016/j.bbagrm.2014.11.009] [Citation(s) in RCA: 272] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 11/21/2014] [Accepted: 11/26/2014] [Indexed: 12/27/2022]
Abstract
Cancer cells are exposed to adverse conditions in the tumor microenvironment, and utilize post-transcriptional control mechanisms to re-program gene expression in ways that enhance cell survival. Stress granules and processing bodies are RNA-containing granules that contribute to this process by modulating cellular signaling pathways, metabolic machinery, and stress response programs. This review examines evidence implicating RNA granules in the pathogenesis of cancer and discusses their potential as targets for anticancer therapies. This article is part of a Special Issue entitled: Translation and Cancer.
Collapse
Affiliation(s)
- Paul Anderson
- Division of Rheumatology, Immunology, and Allergy, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Medicine, Harvard Medical School, Boston, MA 02115, USA.
| | - Nancy Kedersha
- Division of Rheumatology, Immunology, and Allergy, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
| | - Pavel Ivanov
- Division of Rheumatology, Immunology, and Allergy, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Medicine, Harvard Medical School, Boston, MA 02115, USA.
| |
Collapse
|
62
|
SAMD9 is an innate antiviral host factor with stress response properties that can be antagonized by poxviruses. J Virol 2014; 89:1925-31. [PMID: 25428864 DOI: 10.1128/jvi.02262-14] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
We show that SAMD9 is an innate host antiviral stress response element that participates in the formation of antiviral granules. Poxviruses, myxoma virus and vaccinia virus specifically, utilize a virus-encoded host range factor(s), such as a member of the C7L superfamily, to antagonize SAMD9 to prevent granule formation in a eukaryotic initiation factor 2α (eIF2α)-independent manner. When SAMD9 is stimulated due to failure of the viral antagonism during infection, the resulting antiviral granules exhibit properties different from those of the canonical stress granules.
Collapse
|
63
|
Khaperskyy DA, Emara MM, Johnston BP, Anderson P, Hatchette TF, McCormick C. Influenza a virus host shutoff disables antiviral stress-induced translation arrest. PLoS Pathog 2014; 10:e1004217. [PMID: 25010204 PMCID: PMC4092144 DOI: 10.1371/journal.ppat.1004217] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Accepted: 05/14/2014] [Indexed: 12/22/2022] Open
Abstract
Influenza A virus (IAV) polymerase complexes function in the nucleus of infected cells, generating mRNAs that bear 5′ caps and poly(A) tails, and which are exported to the cytoplasm and translated by host machinery. Host antiviral defences include mechanisms that detect the stress of virus infection and arrest cap-dependent mRNA translation, which normally results in the formation of cytoplasmic aggregates of translationally stalled mRNA-protein complexes known as stress granules (SGs). It remains unclear how IAV ensures preferential translation of viral gene products while evading stress-induced translation arrest. Here, we demonstrate that at early stages of infection both viral and host mRNAs are sensitive to drug-induced translation arrest and SG formation. By contrast, at later stages of infection, IAV becomes partially resistant to stress-induced translation arrest, thereby maintaining ongoing translation of viral gene products. To this end, the virus deploys multiple proteins that block stress-induced SG formation: 1) non-structural protein 1 (NS1) inactivates the antiviral double-stranded RNA (dsRNA)-activated kinase PKR, thereby preventing eIF2α phosphorylation and SG formation; 2) nucleoprotein (NP) inhibits SG formation without affecting eIF2α phosphorylation; 3) host-shutoff protein polymerase-acidic protein-X (PA-X) strongly inhibits SG formation concomitant with dramatic depletion of cytoplasmic poly(A) RNA and nuclear accumulation of poly(A)-binding protein. Recombinant viruses with disrupted PA-X host shutoff function fail to effectively inhibit stress-induced SG formation. The existence of three distinct mechanisms of IAV-mediated SG blockade reveals the magnitude of the threat of stress-induced translation arrest during viral replication. Like all viruses, Influenza A virus (IAV) is absolutely dependent on host-cell protein synthesis machinery. This dependence makes the virus vulnerable to the innate ability of cells to inhibit protein synthesis in response to various types of stress. This inhibition, termed translation arrest, helps cells survive adverse conditions by re-dedicating their energy to stress responses. When cells arrest translation, they form stress granules: depots of untranslated mRNAs and associated proteins. Translation arrest and formation of stress granules can be induced pharmacologically, and in this work we sought to determine whether stress granule induction would be effective in blocking IAV replication. Here we demonstrate that treatment of cells with inducers of stress granules at early times after infection resulted in blockade of viral protein synthesis and stopped viral replication. At later times post-infection, by contrast, IAV proteins prevented pharmacological induction of stress granules. We identified three viral proteins – more than in any virus to date – that work in concert to prevent stress granule formation. Taken together, our studies reveal a multipronged approach for viral suppression of translation arrest, and identify a window of opportunity early in infection when pharmacological induction of stress granules has a strong antiviral effect.
Collapse
Affiliation(s)
- Denys A. Khaperskyy
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Mohamed M. Emara
- Laboratory of Stem Cell Research, Qatar Biomedical Research Institute, Doha, Qatar
- Department of Virology, School of Veterinary Medicine, Cairo University, Giza, Egypt
- Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Benjamin P. Johnston
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Paul Anderson
- Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Todd F. Hatchette
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Craig McCormick
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
- * E-mail:
| |
Collapse
|
64
|
Akcakanat A, Hong DS, Meric-Bernstam F. Targeting translation initiation in breast cancer. ACTA ACUST UNITED AC 2014; 2:e28968. [PMID: 26779407 PMCID: PMC4705830 DOI: 10.4161/trla.28968] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 04/09/2014] [Accepted: 04/22/2014] [Indexed: 12/23/2022]
Abstract
Over the past 20 years, a better understanding of cancer biology, screening for early detection, improved adjuvant treatment, and targeted therapies have decreased the rate of breast cancer deaths. However, resistance to treatment is common, and new approaches are needed. Deregulation of translation initiation is associated with the commencement and progression of cancer. Often, translation initiation factors are overexpressed and the related signaling pathways activated in human tumors. Recently, a significant number of inhibitors that target translation factors and pathways have become available. These inhibitors are being tested alone or in combination with chemotherapeutic agents in clinical trials. The results are varied, and it is not yet clear which drug treatments most effectively inhibit tumor growth. This review highlights the pathways and downstream effects of the activation of translation and discusses targeting the control of translation initiation as a therapeutic approach in cancer, focusing on breast cancer clinical trials.
Collapse
Affiliation(s)
- Argun Akcakanat
- Department of Investigational Cancer Therapeutics; Houston, TX USA
| | - David S Hong
- Department of Investigational Cancer Therapeutics; Houston, TX USA
| | - Funda Meric-Bernstam
- Department of Investigational Cancer Therapeutics; Houston, TX USA; Department of Surgical Oncology; The University of Texas MD Anderson Cancer Center; Houston, TX USA
| |
Collapse
|
65
|
Wender PA, Donnelly AC, Loy BA, Near KE, Staveness D. Rethinking the Role of Natural Products: Function-Oriented Synthesis, Bryostatin, and Bryologs. METHODS AND PRINCIPLES IN MEDICINAL CHEMISTRY 2014. [DOI: 10.1002/9783527676545.ch14] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
|
66
|
Low WK, Li J, Zhu M, Kommaraju SS, Shah-Mittal J, Hull K, Liu JO, Romo D. Second-generation derivatives of the eukaryotic translation initiation inhibitor pateamine A targeting eIF4A as potential anticancer agents. Bioorg Med Chem 2013; 22:116-25. [PMID: 24359706 DOI: 10.1016/j.bmc.2013.11.046] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 11/15/2013] [Accepted: 11/23/2013] [Indexed: 02/06/2023]
Abstract
A series of pateamine A (1) derivatives were synthesized for structure/activity relationship (SAR) studies and a selection of previous generation analogs were re-evaluated based on current information regarding the mechanism of action of these translation inhibitors. Structural modifications in the new generation of derivatives focused on alterations to the C19-C22 Z,E-diene and the trienyl side chain of the previously described simplified, des-methyl, des-amino pateamine A (DMDAPatA, 2). Derivatives were tested for anti-proliferative activity in cell culture and for inhibition of mammalian cap-dependent translation in vitro. Activity was highly dependent on the rigidity and conformation of the macrolide and the functionality of the side chain. The only well tolerated substitutions were replacement of the N,N-dimethyl amino group found on the side chain of 2 with other tertiary amine groups. SAR reported here suggests that this site may be modified in future studies to improve serum stability, cell-type specificity, and/or specificity towards rapidly proliferating cells.
Collapse
Affiliation(s)
- Woon-Kai Low
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, 8000 Utopia Parkway, Queens, NY 11439, USA.
| | - Jing Li
- Natural Product LINCHPIN Laboratory, Department of Chemistry, Texas A&M University, P.O. Box 300012, College Station, TX 77842-3012, USA
| | - Mingzhao Zhu
- Natural Product LINCHPIN Laboratory, Department of Chemistry, Texas A&M University, P.O. Box 300012, College Station, TX 77842-3012, USA
| | - Sai Shilpa Kommaraju
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, 8000 Utopia Parkway, Queens, NY 11439, USA
| | - Janki Shah-Mittal
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, 8000 Utopia Parkway, Queens, NY 11439, USA
| | - Ken Hull
- Natural Product LINCHPIN Laboratory, Department of Chemistry, Texas A&M University, P.O. Box 300012, College Station, TX 77842-3012, USA
| | - Jun O Liu
- Department of Pharmacology and Molecular Sciences, Johns Hopkins School of Medicine, 725 North Wolfe St., Baltimore, MD 21205, USA
| | - Daniel Romo
- Natural Product LINCHPIN Laboratory, Department of Chemistry, Texas A&M University, P.O. Box 300012, College Station, TX 77842-3012, USA; Department of Chemistry, Texas A&M University, P.O. Box 300012, College Station, TX 77842-3012, USA.
| |
Collapse
|
67
|
Ortega HE, Graupner PR, Asai Y, Tendyke K, Qiu D, Shen YY, Rios N, Arnold AE, Coley PD, Kursar TA, Gerwick WH, Cubilla-Rios L. Mycoleptodiscins A and B, cytotoxic alkaloids from the endophytic fungus Mycoleptodiscus sp. F0194. JOURNAL OF NATURAL PRODUCTS 2013; 76:741-744. [PMID: 23560689 DOI: 10.1021/np300792t] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Two novel reddish-orange alkaloids, mycoleptodiscin A (1) and mycoleptodiscin B (2), were isolated from liquid cultures of the endophytic fungus Mycoleptodiscus sp. that had been isolated from Desmotes incomparabilis in Panama. Elucidation of their structures was accomplished using 1D and 2D NMR spectroscopy in combination with IR spectroscopic and MS data. These compounds are indole-terpenes with a new skeleton uncommon in nature. Mycoleptodiscin B (2) was active in inhibiting the growth of cancer cell lines with IC50 values in the range 0.60-0.78 μM.
Collapse
Affiliation(s)
- Humberto E Ortega
- Laboratory of Tropical Bioorganic Chemistry, Faculty of Natural, Exact Science and Technology, University of Panama, Panama
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
68
|
Mejia EJ, Magranet LB, De Voogd NJ, TenDyke K, Qiu D, Shen YY, Zhou Z, Crews P. Structures and cytotoxic evaluation of new and known acyclic Ene-Ynes from an American Samoa Petrosia sp. Sponge. JOURNAL OF NATURAL PRODUCTS 2013; 76:425-32. [PMID: 23368996 PMCID: PMC3745307 DOI: 10.1021/np3008446] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Four new compounds, (-)-petrosynoic acids A-D (1-4), and five known congeners, pellynols A (5), C (6), D (7), F (8), and I (9), were isolated from a Petrosia sp. marine sponge collected in American Samoa. Isolation work was guided by cytotoxicity against human lung cancer cells (H460). The structures of the C31-C33 polyacetylenes (1-9) were determined on the basis of 1D- and 2D-NMR analysis, mass spectrometry, and comparison of specific rotation values. Compounds 1-9 were found to be broadly cytotoxic with limited selectivity for cancer cells, as they were all moderately active against the A2058 (melanoma), H522-T1 (lung), and H460 (lung) human cancer cell lines as well as IMR-90 quiescent human fibroblast cells.
Collapse
Affiliation(s)
- Eric J. Mejia
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064
| | - Lindsay B. Magranet
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064
| | | | - Karen TenDyke
- Eisai Inc., 4 Corporate Drive, Andover, Massachussetts 01810
| | - Dayong Qiu
- Eisai Inc., 4 Corporate Drive, Andover, Massachussetts 01810
| | | | - Zhongrui Zhou
- QB3/Chemistry Mass Spectrometry Facility, University of California, Berkeley, CA 94720
| | - Phillip Crews
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064
| |
Collapse
|
69
|
Cencic R, Pelletier J. Throwing a monkey wrench in the motor: targeting DExH/D box proteins with small molecule inhibitors. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:894-903. [PMID: 23385390 DOI: 10.1016/j.bbagrm.2013.01.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 01/21/2013] [Accepted: 01/24/2013] [Indexed: 01/04/2023]
Abstract
DExH/D box proteins are molecular motors that utilize the energy derived from NTP hydrolysis to perform work - from helicases that remodel RNA to RNPases that alter RNA-protein complexes. Members of this class of proteins are uniquely placed along the RNA information highway to regulate the flow of genetic information. They have been implicated in a number of nodal points encompassing nuclear, cytoplasmic, and organellar RNA-based processes. The identification and characterization of three unique natural products that selectively inhibit the activity of eukaryotic initiation factor (eIF)4A (DDX2) has provided proof-of-principle that the activity of DExH/D box family members can be selectively targeted. Extending these achievements to other DExH/D box proteins is an important future challenge for drugging this family of proteins. This article is part of a Special Issue entitled: The Biology of RNA helicases - Modulation for life.
Collapse
Affiliation(s)
- Regina Cencic
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada.
| | | |
Collapse
|
70
|
Aberrations in translational regulation are associated with poor prognosis in hormone receptor-positive breast cancer. Breast Cancer Res 2012; 14:R138. [PMID: 23102376 PMCID: PMC4053117 DOI: 10.1186/bcr3343] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Accepted: 10/17/2012] [Indexed: 12/25/2022] Open
Abstract
Introduction Translation initiation is activated in cancer through increase in eukaryotic initiation factor 4E (eIF4E), eIF4G, phosphorylated eIF4E-binding protein (p4E-BP1) and phosphorylated ribosomal protein S6 (pS6), and decreased programmed cell death protein 4 (pdcd4), a translational inhibitor. Further, translation elongation is deregulated though alterations in eukaryotic elongation factor 2 (eEF2) and eEF2 kinase (eEF2K). We sought to determine the association of these translational aberrations with clinical-pathologic factors and survival outcomes in hormone receptor-positive breast cancer. Methods Primary tumors were collected from 190 patients with Stage I to III hormone receptor-positive breast cancer. Expression of eIF4E, eIF4G, 4E-BP1, p4E-BP1 T37/46, p4E-BP1 S65, p4E-BP1 T70, S6, pS6 S235/236, pS6 S240/244, pdcd4, eEF2 and eEF2K was assessed by reverse phase protein arrays. Univariable and multivariable analyses for recurrence-free survival (RFS) and overall survival (OS) were performed. Results High eEF2, S6, pS6 S240/244, p4E-BP1 T70, and low pdcd4 were significantly associated with node positivity. Median follow-up for living patients was 96 months. High p4E-BP1 T36/47, p4E-BP1 S65, p4E-BP1 T70 and 4E-BP1 were associated with worse RFS. High p4E-BP1 T70 and pS6 S235/236, and low pdcd4, were associated with worse OS. In multivariable analysis, in addition to positive nodes, p4E-BP1 S65 remained a significant predictor of RFS (HR = 1.62, 95% CI = 1.13-2.31; P = 0.008). In addition to age, pS6 S235/236 (HR = 1.73, 95% CI = 1.03-2.90, P = 0.039), eEF2K (HR = 2.19, 95% CI = 1.35-3.56, P = 0.002) and pdcd4 (HR = 0.42, 95% CI = 0.25-0.70, P = 0.001) were associated with OS. Conclusions Increased pS6, p4E-BP1, eEF2K and decreased pdcd4 are associated with poor prognosis in hormone receptor-positive breast cancer, suggesting their role as prognostic markers and therapeutic targets.
Collapse
|
71
|
Grzmil M, Hemmings BA. Translation Regulation as a Therapeutic Target in Cancer: Figure 1. Cancer Res 2012; 72:3891-900. [DOI: 10.1158/0008-5472.can-12-0026] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
72
|
Di Marco S, Cammas A, Lian XJ, Kovacs EN, Ma JF, Hall DT, Mazroui R, Richardson J, Pelletier J, Gallouzi IE. The translation inhibitor pateamine A prevents cachexia-induced muscle wasting in mice. Nat Commun 2012; 3:896. [PMID: 22692539 PMCID: PMC3621420 DOI: 10.1038/ncomms1899] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Accepted: 05/09/2012] [Indexed: 12/16/2022] Open
Abstract
Cachexia, or muscle-wasting syndrome, is one of the major causes of death in patients affected by diseases such as cancer, AIDS and sepsis. However, no effective anti-cachectic treatment is currently available. Here we show that a low dose of pateamine A, an inhibitor of translation initiation, prevents muscle wasting caused by the cytokines interferon γ and tumour necrosis factor α or by C26-adenocarcinoma tumours. Surprisingly, although high doses of pateamine A abrogate general translation, low doses selectively inhibit the expression of pro-cachectic factors such as inducible nitric oxide synthase. This selectivity depends on the 5'UTR of inducible nitric oxide synthase messenger RNA (mRNA) that, unlike the 5'UTR of MyoD mRNA, promotes the recruitment of inducible nitric oxide synthase mRNA to stress granules, where its translation is repressed. Collectively, our data provide a proof of principle that nontoxic doses of compounds such as pateamine A could be used as novel drugs to combat cachexia-induced muscle wasting.
Collapse
Affiliation(s)
- Sergio Di Marco
- Department of Biochemistry, Rosalind and Morris Goodman Cancer Center, McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec, Canada
| | | | | | | | | | | | | | | | | | | |
Collapse
|
73
|
Abstract
RNA helicases unwind their RNA substrates in an ATP-dependent reaction, and are central to all cellular processes involving RNA. They have important roles in viral life cycles, where RNA helicases are either virus-encoded or recruited from the host. Vertebrate RNA helicases sense viral infections, and trigger the innate antiviral immune response. RNA helicases have been implicated in protozoic, bacterial and fungal infections. They are also linked to neurological disorders, cancer, and aging processes. Genome-wide studies continue to identify helicase genes that change their expression patterns after infection or disease outbreak, but the mechanism of RNA helicase action has been defined for only a few diseases. RNA helicases are prognostic and diagnostic markers and suitable drug targets, predominantly for antiviral and anti-cancer therapies. This review summarizes the current knowledge on RNA helicases in infection and disease, and their growing potential as drug targets.
Collapse
Affiliation(s)
- Lenz Steimer
- University of Muenster, Institute for Physical Chemistry, Muenster, Germany
| | | |
Collapse
|
74
|
Leung A, Todorova T, Ando Y, Chang P. Poly(ADP-ribose) regulates post-transcriptional gene regulation in the cytoplasm. RNA Biol 2012; 9:542-8. [PMID: 22531498 DOI: 10.4161/rna.19899] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Since its discovery in 1963, poly(ADP-ribose) (pADPr) has been shown to play important functions in the nucleus of multicellular eukaryotes. Each of these functions centers upon DNA metabolism, including DNA-damage repair, chromatin remodeling, transcription and telomere functions. We recently described two novel functions for pADPr in the cytoplasm, both of which involve RNA metabolism - 1) the assembly of cytoplasmic stress granules, cellular macrostructures that aggregate translationally stalled mRNA/protein complexes, and 2) modulation of microRNA activities. Multiple stress granule-localized, post-transcriptional gene regulators, including microRNA-binding argonaute family members, are substrates for pADPr modification and are increasingly modified by pADPr upon stress. Interestingly, the cytoplasmic RNA regulatory functions for PARPs are likely mediated through activities of catalytically inactive PARP-13/ARTD13/ZC3HAV1/ZAP and mono/poly(ADP-ribose)-synthesizing enzymes, including PARP-5a/ARTD5/TNKS1, PARP-12/ARTD12/ZC3HDC1 and PARP-15/ARTD7/BAL3. These data are consistent with other recent work, which suggests that mono(ADP-ribosyl)ated residues can be poly(ADP-ribosyl)ated by different enzymes.
Collapse
Affiliation(s)
- Anthony Leung
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.
| | | | | | | |
Collapse
|
75
|
Abstract
Protein synthesis is a complex, tightly regulated process in eukaryotic cells and its deregulation is a hallmark of many cancers. Translational control occurs primarily at the rate-limiting initiation step, where ribosomal subunits are recruited to template mRNAs through the concerted action of several eukaryotic initiation factors (eIFs). One factor that interacts with both the mRNA and ribosomes, and appears limiting for translation is eIF4F, a complex composed of the cap-binding protein, eIF4E; the scaffold protein, eIF4G; and the ATP-dependent DEAD-box helicase, eIF4A. eIF4E appears to play an important role in tumor initiation and progression since its overexpression can cooperate with oncogenes to accelerate transformation in cell lines and animal models, and its levels are elevated in many human cancers. This, therefore, represents a vulnerability for transformed cells, and presents an opportunity for therapeutic intervention. In this review, we discuss approaches for targeting eIF4F activity.
Collapse
|
76
|
Abstract
A defining feature of many cancers is deregulated translational control. Typically, this occurs at the level of recruitment of the 40S ribosomes to the 5'-cap of cellular messenger RNAs (mRNAs), the rate-limiting step of protein synthesis, which is controlled by the heterotrimeric eukaryotic initiation complex eIF4F. Thus, eIF4F in particular, and translation initiation in general, represent an exploitable vulnerability and unique opportunity for therapeutic intervention in many transformed cells. In this article, we discuss the development, mode of action and biological activity of a number of small-molecule inhibitors that interrupt PI3K/mTOR signaling control of eIF4F assembly, as well as compounds that more directly block eIF4F activity.
Collapse
Affiliation(s)
- Abba Malina
- Department of Biochemistry and McGill University, Montréal, Québec H3G 1Y6, Canada
| | | | | |
Collapse
|
77
|
|
78
|
Reiner JE, Datta PK. TGF-beta-dependent and -independent roles of STRAP in cancer. Front Biosci (Landmark Ed) 2011; 16:105-15. [PMID: 21196161 DOI: 10.2741/3678] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The serine-threonine kinase receptor-associated protein (STRAP) was initially identified as a putative inhibitor of the canonical TGF-beta signaling pathway. Because the Smad-dependent TGF-beta pathway negatively regulates cellular growth, early functional studies suggested that STRAP behaves as an oncogene. Indeed, a correlation between STRAP overexpression and various cancers has been identified. With the emergence of new studies on the biological function of STRAP, it is becoming clear that STRAP regulates several distinct cellular processes and modulates multiple signaling pathways. While STRAP itself does not possess enzymatic activity, it appears that STRAP influences biological processes through associations with cellular proteins. In this review, we will describe the TGF-beta-dependent and -independent functions of STRAP and provide a context for the significance of STRAP activity in the development of cancer.
Collapse
Affiliation(s)
- Jennifer Elisabeth Reiner
- Cancer Biology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | | |
Collapse
|
79
|
Abstract
Natural products have evolved to encompass a broad spectrum of chemical and functional diversity. It is this diversity, along with their structural complexity, that enables nature's small molecules to target a nearly limitless number of biological macromolecules and to often do so in a highly selective fashion. Because of these characteristics, natural products have seen great success as therapeutic agents. However, this vast pool of compounds holds much promise beyond the development of future drugs. These features also make them ideal tools for the study of biological systems. Recent examples of the use of natural products and their derivatives as chemical probes to explore biological phenomena and assemble biochemical pathways are presented here.
Collapse
Affiliation(s)
- Erin E. Carlson
- Departments of Chemistry and Molecular and Cellular Biochemistry, Indiana University, 212 S. Hawthorne Drive, Bloomington, Indiana 47405
| |
Collapse
|
80
|
Abstract
Following transcription, genomic information begins a long journey toward translation of its nucleotide sequence into the amino acids of a protein. In eukaryotes, synthesized pre-mRNAs become processed to mature mRNAs by 5'-end capping, splicing, 3'-end cleavage and polyadenylation in the nucleus, before being scrutinized for premature stop codons. Each step requires high precision and control to ensure that an intact and readable message is exported to the cytoplasm before finally becoming translated. Two important aspects of these processes are accurately managed by ribonucleoprotein machineries-the spliceosome and the ribosome. Recently, several natural products targeting these macromolecular assemblies have been reported. For the first time in eukaryotes, these molecules allow chemical disruption and dissection of the sophisticated machinery that regulates post-transcriptional events. Beyond their great potential as bioprobes for investigating mRNA regulation and protein synthesis, these compounds also show promise in opening new therapeutic approaches.
Collapse
|
81
|
Salinomycin induces apoptosis and overcomes apoptosis resistance in human cancer cells. Biochem Biophys Res Commun 2009; 390:743-9. [PMID: 19835841 DOI: 10.1016/j.bbrc.2009.10.042] [Citation(s) in RCA: 145] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2009] [Accepted: 10/09/2009] [Indexed: 12/13/2022]
Abstract
Salinomycin is a polyether antibiotic isolated from Streptomyces albus that acts in different biological membranes as a ionophore with a preference for potassium. It is widely used as an anticoccidial drug in poultry and is fed to ruminants to improve nutrient absorption and feed efficiency. Salinomycin has recently been shown to selectively deplete human breast cancer stem cells from tumorspheres and to inhibit breast cancer growth and metastasis in mice. We show here that salinomycin induces massive apoptosis in human cancer cells of different origin, but not in normal cells such as human T lymphocytes. Moreover, salinomycin is able to induce apoptosis in cancer cells that exhibit resistance to apoptosis and anticancer agents by overexpression of Bcl-2, P-glycoprotein or 26S proteasomes with enhanced proteolytic activity. Salinomycin activates a distinct apoptotic pathway that is not accompanied by cell cycle arrest and that is independent of tumor suppressor protein p53, caspase activation, the CD95/CD95L system and the proteasome. Thus, salinomycin should be considered as a novel and effective anticancer agent that overcomes multiple mechanisms of apoptosis resistance in human cancer cells.
Collapse
|