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Wang H, Sharma L, Lu J, Finch P, Fletcher S, Prochownik EV. Structurally diverse c-Myc inhibitors share a common mechanism of action involving ATP depletion. Oncotarget 2016; 6:15857-70. [PMID: 26036281 PMCID: PMC4599242 DOI: 10.18632/oncotarget.4327] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 04/10/2015] [Indexed: 12/29/2022] Open
Abstract
The c-Myc (Myc) oncoprotein is deregulated in a large proportion of diverse human cancers. Considerable effort has therefore been directed at identifying pharmacologic inhibitors as potential anti-neoplastic agents. Three such groups of small molecule inhibitors have been described. The first is comprised of so-called “direct” inhibitors, which perturb Myc's ability to form productive DNA-binding heterodimers in association with its partner, Max. The second group is comprised of indirect inhibitors, which largely function by targeting the BET-domain protein BRD4 to prevent the proper formation of transcriptional complexes that assemble in response to Myc-Max DNA binding. Thirdly, synthetic lethal inhibitors cause the selective apoptosis of Myc over-expressing either by promoting mitotic catastrophe or altering Myc protein stability. We report here a common mechanism by which all Myc inhibitors, irrespective of class, lead to eventual cellular demise. This involves the depletion of ATP stores due to mitochondrial dysfunction and the eventual down-regulation of Myc protein. The accompanying metabolic de-regulation causes neutral lipid accumulation, cell cycle arrest, and an attempt to rectify the ATP deficit by up-regulating AMP-activated protein kinase (AMPK). These responses are ultimately futile due to the lack of functional Myc to support the requisite anabolic response. Finally, the effects of Myc depletion on ATP levels, cell cycle arrest, differentiation and AMPK activation can be mimicked by pharmacologic inhibition of the mitochondrial electron transport chain without affecting Myc levels. Thus, all Myc inhibitors promote a global energy collapse that appears to underlie many of their phenotypic consequences.
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Affiliation(s)
- Huabo Wang
- Division of Hematology/Oncology, Children's Hospital of Pittsburgh of University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Lokendra Sharma
- Division of Hematology/Oncology, Children's Hospital of Pittsburgh of University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Jie Lu
- Division of Hematology/Oncology, Children's Hospital of Pittsburgh of University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Paul Finch
- Division of Hematology/Oncology, Children's Hospital of Pittsburgh of University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Steven Fletcher
- Department of Pharmaceutical Sciences, The University of Maryland School of Pharmacy, Baltimore, MD, USA.,The Greenebaum Cancer Center, Baltimore, MD, USA
| | - Edward V Prochownik
- Division of Hematology/Oncology, Children's Hospital of Pittsburgh of University of Pittsburgh Medical Center, Pittsburgh, PA, USA.,Department of Microbiology and Molecular Genetics, The University of Pittsburgh, Pittsburgh, PA, USA.,The University of Pittsburgh Cancer Institute, Pittsburgh, PA, USA
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Fernández-Mejia C, Peralta-Zaragoza O, Cerezo-Roman J, Navarro-Duque C, Barrera-Rodríguez R, Martínez-Valdez H, Madrid-Marina V. Regulation of gene expression of adenosine deaminase, purine nucleoside phosphorylase and terminal deoxynucleotidyl transferase by dexamethasone and cAMP in human leukemic cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1995; 370:249-52. [PMID: 7660900 DOI: 10.1007/978-1-4615-2584-4_52] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- C Fernández-Mejia
- Unidad de Genética de la Nutrición, Instituto Nacional de Pediatría, México
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Chinsky JM, Ramamurthy V, Fanslow WC, Ingolia DE, Blackburn MR, Shaffer KT, Higley HR, Trentin JJ, Rudolph FB, Knudsen TB. Developmental expression of adenosine deaminase in the upper alimentary tract of mice. Differentiation 1990; 42:172-83. [PMID: 2187728 DOI: 10.1111/j.1432-0436.1990.tb00759.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The distribution and localization of adenosine deaminase (ADA) was studied during postnatal development of the alimentary tract in mice. There was detectable enzyme activity in all organs examined, but a range of more than 10,000 fold in the relative levels of specific activity was observed among adult tissues. A comprehensive survey of multiple adult tissues revealed that the highest levels of ADA occur in the upper alimentary tract (tongue, esophagus, forestomach, proximal small intestine). Immunohistochemical analysis revealed that ADA was predominantly localized to the epithelial lining of the alimentary mucosa: the keratinized squamous epithelium that lines the forestomach, esophagus, and surface of the tongue; and the simple columnar epithelium of the proximal small intestine (duodenum, proximal jejunum). Biochemical analysis revealed that ADA was one of the most abundant proteins of these mucosal tissue layers, accounting for 5%-20% of the total soluble protein. Tissue-specific differences in ADA activity correlated both with levels of immunoreactive protein and RNA abundance. The level of ADA activity in the upper alimentary tissues was subject to pronounced developmental control, being low at birth and achieving very high levels within the first few weeks of postnatal life. The appearance in development of ADA-immunoreactivity coincided with maturation of the mucosal epithelium. These results suggest that ADA is subject to strong cell-specific developmental regulation during functional differentiation of certain foregut derivatives in mice.
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Affiliation(s)
- J M Chinsky
- Verna and Marrs McLean Department of Biochemistry, Baylor College of Medicine, Houston, TX 77030
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Valerio D, van der Putten H, Botteri FM, Hoogerbrugge PM. Activity of the adenosine deaminase promoter in transgenic mice. Nucleic Acids Res 1988; 16:10083-97. [PMID: 3057438 PMCID: PMC338838 DOI: 10.1093/nar/16.21.10083] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The promoter of the human gene for adenosine deaminase (ADA) is extremely G/C-rich, contains several G/C-box motifs (GGGCGGG) and lacks any apparent TATA or CAAT boxes. These features are commonly found in promoters of genes that lack a strong tissue specificity, and are referred to as "housekeeping genes". Like other housekeeping genes, the ADA gene is expressed in all tissues. However, there is a considerable variation in the levels of expression of the ADA protein in different tissues. In order to study the activity of the ADA promoter, transgenic mice were generated that harbor a chimeric gene composed of the ADA promoter linked to a reporter gene encoding the bacterial enzyme Chloramphenicol Acetyl Transferase (CAT). These mice reproducibly showed CAT expression in all tissues examined, including the hemopoietic organs (spleen, thymus and bone marrow). However, examination of the actual cell types expressing the CAT gene revealed the ADA promoter to be inactive in the hemopoietic cells. This was substantiated by a transplantation experiment in which bone marrow from ADA-CAT transgenic mice was used to reconstitute the hemopoietic compartment of lethally irradiated mice. The engrafted recipients revealed strongly reduced CAT activity in their hemopoietic organs. The lack of expression in hemopoietic cells was further shown to be correlated with a hypermethylated state of the transgene. Combined, our data suggest that the ADA promoter sequences tested can direct expression in a wide variety of tissues as expected for a regular housekeeping gene promoter. However, the activity of the ADA promoter fragment did not reflect the tissue-specific variations in expression levels of the endogenous ADA gene. Additionally, regulatory elements are needed for expression in the hemopoietic cells.
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Affiliation(s)
- D Valerio
- Radiobiological Institute TNO, Rijswijk, The Netherlands
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Berkvens TM, Schoute F, van Ormondt H, Meera Khan P, van der Eb AJ. Adenosine deaminase gene expression is regulated posttranscriptionally in the nucleus. Nucleic Acids Res 1988; 16:3255-68. [PMID: 3163799 PMCID: PMC336492 DOI: 10.1093/nar/16.8.3255] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The housekeeping enzyme adenosine deaminase (ADA) shows a large variation in tissue-specific expression ranging from 1 Iu in red blood cells to 880 Iu in thymocytes. We investigated the acute lymphocytic leukemic cell line Molt-4 (660 Iu ADA/g protein) and the promyelocytic cell line HL-60 (38 Iu ADA/g protein) as a model system to determine the levels at which the tissue-specific expression of ADA is regulated. From our results it can be concluded that the almost 20-fold difference in ADA expression between Molt-4 and HL-60 is the result of differences in the post-transcriptional processing and/or stability of ADA pre-mRNA within the nucleus.
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Affiliation(s)
- T M Berkvens
- Department of Medical Biochemistry, Sylvius Laboratories, Leiden, The Netherlands
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