1151
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Abstract
As described by Warburg more than 50 years ago, tumour cells maintain a high glycolytic rate even in conditions of adequate oxygen supply. However, most of tumours are subjected to hypoxic conditions due to the abnormal vasculature that supply them with oxygen and nutrients. Thus, glycolysis is essential for tumour survival and spread. A key step in controlling glycolytic rate is the conversion of fructose-6-P to fructose-1,6-P(2) by 6-phosphofructo-1-kinase (PFK-1). The activity of PFK-1 is allosterically controlled by fructose-2,6-P(2), the product of the enzymatic activity of a dual kinase/phosphatase family of enzymes (PFKFB1-4) that are increased in a significant number of tumour types. In turn, these enzymes are induced by hypoxia through the activation of the HIF-1 complex (hypoxia-inducible complex-1), a transcriptional activator that controls the expression of most of hypoxia-regulated genes. HIF-1 complex is overexpressed in a variety of tumours and its expression appears to correlate with poor prognosis and responses to chemo or radiotherapy. Thus, targeting PFKFB enzymes, either directly or through inhibition of HIF-1, appears as a promising approach for the treatment of certain tumours.
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Affiliation(s)
- Ramon Bartrons
- Unitat Bioquímica i Biologia Molecular, Departament de Ciències Fisiològiques, Campus de Ciències de la Salut, IDIBELL--Universitat de Barcelona, Barcelona, Spain.
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1152
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Kawata S. Association of digestive organ disease with metabolic syndrome: role of adipocytokine and its molecular mechanisms. Clin J Gastroenterol 2008; 1:1-6. [DOI: 10.1007/s12328-008-0001-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2008] [Accepted: 02/05/2008] [Indexed: 01/09/2023]
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1153
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Kondoh H. Cellular life span and the Warburg effect. Exp Cell Res 2008; 314:1923-8. [PMID: 18410925 DOI: 10.1016/j.yexcr.2008.03.007] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2008] [Revised: 03/11/2008] [Accepted: 03/12/2008] [Indexed: 10/22/2022]
Abstract
Enhanced glycolysis is observed in most of cancerous cells and tissues, called as the Warburg effect. Recent advance in senescent biology implicates that the metabolic shift to enhanced glycolysis would be involved in the early stage during multi-step tumorigenesis in vivo. Enhanced glycolysis is essential both in the step of immortalization and transformation, as it renders cells resistant to oxidative stress and adaptive to hypoxic condition, respectively. ES, immortalized primary, and cancerous cells display the common concerted metabolic shift, including enhanced glycolysis with reduced mitochondrial respiration by poorly characterized mechanism. Discovery of a novel regulatory mechanism for such a metabolic shift might be essential for the future development of cancer diagnosis and anti-cancer therapy.
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Affiliation(s)
- Hiroshi Kondoh
- Department of Geriatric Medicine, Graduate School of Medicine, Kyoto University, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto, 606-8507, Japan.
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1154
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Premature senescence of human endothelial cells induced by inhibition of glutaminase. Biogerontology 2008; 9:247-59. [PMID: 18317946 DOI: 10.1007/s10522-008-9134-x] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Accepted: 02/21/2008] [Indexed: 10/22/2022]
Abstract
Cellular senescence is now recognized as an important mechanism of tumor suppression, and the accumulation of senescent cells may contribute to the aging of various human tissues. Alterations of the cellular energy metabolism are considered key events in tumorigenesis and are also known to play an important role for aging processes in lower eukaryotic model systems. In this study, we addressed senescence-associated changes in the energy metabolism of human endothelial cells, using the HUVEC model of in vitro senescence. We observed a drastic reduction in cellular ATP levels in senescent endothelial cells. Although consumption of glucose and production of lactate significantly increased in senescent cells, no correlation was found between both metabolite conversion rates, neither in young endothelial cells nor in the senescent cells, which indicates that glycolysis is not the main energy source in HUVEC. On the other hand, glutamine consumption was increased in senescent HUVEC and inhibition of glutaminolysis by DON, a specific inhibitor of glutaminase, led to a significant reduction in the proliferative capacity of both early passage and late passage cells. Moreover, inhibition of glutaminase activity induced a senescent-like phenotype in young HUVEC within two passages. Together, the data indicate that glutaminolysis is an important energy source in endothelial cells and that alterations in this pathway play a role in endothelial cell senescence.
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1155
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Gogvadze V, Orrenius S, Zhivotovsky B. Mitochondria in cancer cells: what is so special about them? Trends Cell Biol 2008; 18:165-73. [PMID: 18296052 DOI: 10.1016/j.tcb.2008.01.006] [Citation(s) in RCA: 460] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2007] [Revised: 01/22/2008] [Accepted: 01/23/2008] [Indexed: 02/06/2023]
Abstract
The past decade has revealed a new role for the mitochondria in cell metabolism--regulation of cell death pathways. Considering that most tumor cells are resistant to apoptosis, one might question whether such resistance is related to the particular properties of mitochondria in cancer cells that are distinct from those of mitochondria in non-malignant cells. This scenario was originally suggested by Otto Warburg, who put forward the hypothesis that a decrease in mitochondrial energy metabolism might lead to development of cancer. This review is devoted to the analysis of mitochondrial function in cancer cells, including the mechanisms underlying the upregulation of glycolysis, and how intervention with cellular bioenergetic pathways might make tumor cells more susceptible to anticancer treatment and induction of apoptosis.
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Affiliation(s)
- Vladimir Gogvadze
- Institute of Environmental Medicine, Division of Toxicology, Karolinska Institutet, Box 210, Stockholm, SE-171 77, Sweden
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1156
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Ahmad IM, Abdalla MY, Aykin-Burns N, Simons AL, Oberley LW, Domann FE, Spitz DR. 2-Deoxyglucose combined with wild-type p53 overexpression enhances cytotoxicity in human prostate cancer cells via oxidative stress. Free Radic Biol Med 2008; 44:826-34. [PMID: 18155176 PMCID: PMC2350201 DOI: 10.1016/j.freeradbiomed.2007.11.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2007] [Revised: 11/08/2007] [Accepted: 11/12/2007] [Indexed: 10/22/2022]
Abstract
Overexpression of the tumor suppressor gene, wild-type p53 (wtp53), using adenoviral vectors (Adp53) has been suggested to kill cancer cells by hydroperoxide-mediated oxidative stress [1,2] and nutrient distress induced by the glucose analog, 2-deoxyglucose (2DG), has been suggested to enhance tumor cell killing by agents that induce oxidative stress via disrupting hydroperoxide metabolism [3,4]. In the current study clonogenic cell killing of PC-3 and DU-145 human prostate cancer cells (lacking functional p53) mediated by 4 h exposure to 50 plaque forming units (pfus)/cell of Adp53 (that caused the enforced overexpression of wtp53) was significantly enhanced by treatment with 2DG. Accumulation of glutathione disulfide was found to be significantly greater in both cell lines treated with 2DG+Adp53 and both cell lines treated with 2DG+Adp53 showed a approximately 2-fold increases in dihydroethidine (DHE) and 5-(and-6)-carboxy-2',7'-dichlorodihydrofluorescein diacetate (CDCFH(2)) oxidation, indicative of increased steady-state levels of O(2)(.-) and hydroperoxides, respectively. Finally, overexpression of catalase or glutathione peroxidase using adenoviral vectors partially, but significantly, protected DU-145 cells from the toxicity induced by 2DG+Adp53 treatment. These results show that treatment of human prostate cancer cells with the combination of 2DG (a nutrient stress) and overexpression of the tumor suppressor gene, wtp53, enhances clonogenic cell killing by a mechanism that involves oxidative stress as well as allowing for the speculation that inhibitors of glucose and hydroperoxide metabolism can be used in combination with Adp53 gene therapy to enhance therapeutic responses.
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Affiliation(s)
- Iman M. Ahmad
- Department of Radiography, The Hashemite University, Al-Zarqa’, Jordan
| | - Maher Y. Abdalla
- The Department of Biology & Biotechnology, The Hashemite University, Al-Zarqa’, Jordan
| | - Nukhet Aykin-Burns
- Free Radical and Radiation Biology Program, Department of Radiation Oncology, Holden Comprehensive Cancer Center, The University of Iowa, Iowa City, IA, USA, 52242
| | - Andrean L. Simons
- Free Radical and Radiation Biology Program, Department of Radiation Oncology, Holden Comprehensive Cancer Center, The University of Iowa, Iowa City, IA, USA, 52242
| | - Larry W. Oberley
- Free Radical and Radiation Biology Program, Department of Radiation Oncology, Holden Comprehensive Cancer Center, The University of Iowa, Iowa City, IA, USA, 52242
| | - Frederick E. Domann
- Free Radical and Radiation Biology Program, Department of Radiation Oncology, Holden Comprehensive Cancer Center, The University of Iowa, Iowa City, IA, USA, 52242
| | - Douglas R. Spitz
- Free Radical and Radiation Biology Program, Department of Radiation Oncology, Holden Comprehensive Cancer Center, The University of Iowa, Iowa City, IA, USA, 52242
- To whom correspondence should be addressed: B180 Medical Laboratories, The University of Iowa, Iowa City, IA, 52242; E-mail: ; Tel.: 319-335-8001. Fax: 319-335-8039
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1157
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Mollet J, Delahodde A, Serre V, Chretien D, Schlemmer D, Lombes A, Boddaert N, Desguerre I, de Lonlay P, Ogier de Baulny H, Munnich A, Rötig A. CABC1 gene mutations cause ubiquinone deficiency with cerebellar ataxia and seizures. Am J Hum Genet 2008; 82:623-30. [PMID: 18319072 DOI: 10.1016/j.ajhg.2007.12.022] [Citation(s) in RCA: 212] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2007] [Revised: 12/06/2007] [Accepted: 12/12/2007] [Indexed: 01/28/2023] Open
Abstract
Coenzyme Q(10) (CoQ(10)) plays a pivotal role in oxidative phosphorylation (OXPHOS) in that it distributes electrons between the various dehydrogenases and the cytochrome segments of the respiratory chain. Primary coenzyme Q(10) deficiency represents a clinically heterogeneous condition suggestive of genetic heterogeneity, and several disease genes have been previously identified. The CABC1 gene, also called COQ8 or ADCK3, is the human homolog of the yeast ABC1/COQ8 gene, one of the numerous genes involved in the ubiquinone biosynthesis pathway. The exact function of the Abc1/Coq8 protein is as yet unknown, but this protein is classified as a putative protein kinase. We report here CABC1 gene mutations in four ubiquinone-deficient patients in three distinct families. These patients presented a similar progressive neurological disorder with cerebellar atrophy and seizures. In all cases, enzymological studies pointed to ubiquinone deficiency. CoQ(10) deficiency was confirmed by decreased content of ubiquinone in muscle. Various missense mutations (R213W, G272V, G272D, and E551K) modifying highly conserved amino acids of the protein and a 1 bp frameshift insertion c.[1812_1813insG] were identified. The missense mutations were introduced into the yeast ABC1/COQ8 gene and expressed in a Saccharomyces cerevisiae strain in which the ABC1/COQ8 gene was deleted. All the missense mutations resulted in a respiratory phenotype with no or decreased growth on glycerol medium and a severe reduction in ubiquinone synthesis, demonstrating that these mutations alter the protein function.
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1158
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Young CD, Anderson SM. Sugar and fat - that's where it's at: metabolic changes in tumors. Breast Cancer Res 2008; 10:202. [PMID: 18304378 PMCID: PMC2374962 DOI: 10.1186/bcr1852] [Citation(s) in RCA: 121] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Tumor cells exhibit an altered metabolism, characterized by increased glucose uptake and elevated glycolysis, which was first recognized by Otto Warburg 70 years ago. Warburg originally hypothesized that these metabolic changes reflected damage to mitochondrial oxidative phosphorylation. Although hypoxia and hypoxia inducible factor can induce transcriptional changes that stimulate glucose transport and glycolysis, it is clear that these changes can occur in cultured tumor or transformed cells cultured under normoxic conditions, and thus there must be genetic alterations independent of hypoxia that can stimulate aerobic glycolysis. In recent years it has become clear that loss of p53 and activation of Akt can induce all or part of the metabolic changes reflected in the Warburg effect. Likewise, changes in expression of lactate dehydrogenase and other glycolytic control enzymes can contribute to increased or altered glycolysis. It is also clear that changes in lipid biosynthesis occur in tumor cells to support increased membrane biosynthesis and perhaps the altered energy needs of the cells. Changes in fatty acid synthase, Spot 14, Akt, and DecR1 (2,4-dienoylcoenzyme A reductase) may underlie altered lipid metabolism in tumor cells and contribute to the ability of tumor cells to proliferate or metastasize. Although these advances provide new therapeutic targets that merit exploration, there remain critical questions to be explored at the mechanistic level; this work may yield insights into tumor cell biology and identify additional therapeutic targets.
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Affiliation(s)
- Christian D Young
- Department of Pathology and Program in Cancer Biology, University of Colorado Denver, Anschutz Medical Campus, East 17th Avenue, Aurora, Colorado 80045, USA
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1159
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In several cell types tumour suppressor p53 induces apoptosis largely via Puma but Noxa can contribute. Cell Death Differ 2008; 15:1019-29. [PMID: 18259198 DOI: 10.1038/cdd.2008.16] [Citation(s) in RCA: 147] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The ability of p53 to induce apoptosis in cells with damaged DNA is thought to contribute greatly to its tumour suppressor function. P53 has been proposed to induce apoptosis via numerous transcriptional targets or even by direct cytoplasmic action. Two transcriptional targets shown to mediate its apoptotic role in several cell types encode Noxa and Puma, BH3-only members of the Bcl-2 family. To test if their functions in p53-dependent apoptosis overlap, we generated mice lacking both. These mice develop normally and no tumours have yet arisen. In embryonic fibroblasts, the absence of both Noxa and Puma prevented induction of apoptosis by etoposide. Moreover, following whole body gamma-irradiation, the loss of both proteins protected thymocytes better than loss of Puma alone. Indeed, their combined deficiency protected thymocytes as strongly as loss of p53 itself. These results indicate that, at least in fibroblasts and thymocytes, p53-induced apoptosis proceeds principally via Noxa and Puma, with Puma having the predominant role in diverse cell types. The absence of tumours in the mice suggests that tumour suppression by p53 requires functions in addition to induction of apoptosis.
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1160
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Wittig R, Coy JF. The Role of Glucose Metabolism and Glucose-Associated Signalling in Cancer. PERSPECTIVES IN MEDICINAL CHEMISTRY 2008. [DOI: 10.1177/1177391x0700100006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Aggressive carcinomas ferment glucose to lactate even in the presence of oxygen. This particular metabolism, termed aerobic glycolysis, the glycolytic phenotype, or the Warburg effect, was discovered by Nobel laureate Otto Warburg in the 1920s. Since these times, controversial discussions about the relevance of the fermentation of glucose by tumours took place; however, a majority of cancer researchers considered the Warburg effect as a non-causative epiphenomenon. Recent research demonstrated, that several common oncogenic events favour the expression of the glycolytic phenotype. Moreover, a suppression of the phenotypic features by either substrate limitation, pharmacological intervention, or genetic manipulation was found to mediate potent tumour-suppressive effects. The discovery of the transketolase-like 1 (TKTL1) enzyme in aggressive cancers may deliver a missing link in the interpretation of the Warburg effect. TKTL1-activity could be the basis for a rapid fermentation of glucose in aggressive carcinoma cells via the pentose phosphate pathway, which leads to matrix acidification, invasive growth, and ultimately metastasis. TKTL1 expression in certain non-cancerous tissues correlates with aerobic formation of lactate and rapid fermentation of glucose, which may be required for the prevention of advanced glycation end products and the suppression of reactive oxygen species. There is evidence, that the activity of this enzyme and the Warburg effect can be both protective or destructive for the organism. These results place glucose metabolism to the centre of pathogenesis of several civilisation related diseases and raise concerns about the high glycaemic index of various food components commonly consumed in western diets.
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Affiliation(s)
- Rainer Wittig
- R-Biopharm AG, Landwehrstrasse 54, 64293 Darmstadt, Germany
| | - Johannes F. Coy
- R-Biopharm AG, Landwehrstrasse 54, 64293 Darmstadt, Germany
- TAVARTIS GmbH, Kroetengasse 10, 64853 Otzberg, Germany
- Dept. Of Gynaecology, University of Würzburg, Josef Schneider Str. 4, 97080 Würzburg, Germany
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1161
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Patterson AD, Li H, Eichler GS, Krausz KW, Weinstein JN, Fornace AJ, Gonzalez FJ, Idle JR. UPLC-ESI-TOFMS-based metabolomics and gene expression dynamics inspector self-organizing metabolomic maps as tools for understanding the cellular response to ionizing radiation. Anal Chem 2008; 80:665-74. [PMID: 18173289 DOI: 10.1021/ac701807v] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Global transcriptomic and proteomic profiling platforms have yielded important insights into the complex response to ionizing radiation (IR). Nonetheless, little is known about the ways in which small cellular metabolite concentrations change in response to IR. Here, a metabolomics approach using ultraperformance liquid chromatography coupled with electrospray time-of-flight mass spectrometry was used to profile, over time, the hydrophilic metabolome of TK6 cells exposed to IR doses ranging from 0.5 to 8.0 Gy. Multivariate data analysis of the positive ions revealed dose- and time-dependent clustering of the irradiated cells and identified certain constituents of the water-soluble metabolome as being significantly depleted as early as 1 h after IR. Tandem mass spectrometry was used to confirm metabolite identity. Many of the depleted metabolites are associated with oxidative stress and DNA repair pathways. Included are reduced glutathione, adenosine monophosphate, nicotinamide adenine dinucleotide, and spermine. Similar measurements were performed with a transformed fibroblast cell line, BJ, and it was found that a subset of the identified TK6 metabolites were effective in IR dose discrimination. The GEDI (Gene Expression Dynamics Inspector) algorithm, which is based on self-organizing maps, was used to visualize dynamic global changes in the TK6 metabolome that resulted from IR. It revealed dose-dependent clustering of ions sharing the same trends in concentration change across radiation doses. "Radiation metabolomics," the application of metabolomic analysis to the field of radiobiology, promises to increase our understanding of cellular responses to stressors such as radiation.
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Affiliation(s)
- Andrew D Patterson
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
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1162
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Keun HC. Biomarker discovery for drug development and translational medicine using metabonomics. ERNST SCHERING FOUNDATION SYMPOSIUM PROCEEDINGS 2008:79-98. [PMID: 18811054 DOI: 10.1007/2789_2008_090] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
There exists at present an urgent desire for better biomarkers, especially in the context of pharmaceutical drug development and in the detection and management of disease. Many researchers in the area of biomarker discovery and development have turned to the "-omics" sciences as a way of addressing these needs. Metabolic profiling, or metabonomics, defines the metabolic phenotype and offers a source of novel biomarkers that have better potential to translate effectively. This review will discuss the broad philosophy and motivations behind metabonomics, and illustrate the case with applications relevant to pharmaceutical development and patient management. Particular focus will be paid to the potential of metabonomics to contribute to biomarker discovery in toxicology and cancer research.
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Affiliation(s)
- H C Keun
- Biomolecular Medicine, Division of Surgery, Oncology, Reproductive Biology and Anaesthetics, Imperial College Faculty of Medicine, Sir Alexander Fleming Building, Exhibition Road, SW7 2AZ South Kensington, London, UK.
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1163
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Chowdhury SKR, Raha S, Tarnopolsky MA, Singh G. Increased expression of mitochondrial glycerophosphate dehydrogenase and antioxidant enzymes in prostate cancer cell lines/cancer. Free Radic Res 2007; 41:1116-24. [PMID: 17886033 DOI: 10.1080/10715760701579314] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The involvement of mitochondrial glycerophosphate dehydrogenase (mGPDH) has previously been established in the production of ROS in prostate cancer cell lines (LNCaP, DU145, PC3 and CL1). The current study demonstrates that the mRNA level of mGPDH in prostate cancer cells is 3.3-8.9-fold higher compared to the normal prostate epithelial cell line, PNT1A. This is consistent with the enzymatic activity and protein level of mGPDH. However, cytochrome c oxidase (COX) activity is 2.9-3.2-fold down-regulated in androgen-independent prostate cancer cell lines. The level of antioxidant enzymes, catalase, MnSOD and CuZnSOD are up-regulated in prostate cancer cell lines. Furthermore, it was observed that the activity of mGPDH is significantly higher in liver tissues from all mice with cancer compared to liver tissues from control mice. These data suggest that the up-regulation of mGPDH, due to a highly glycolytic environment, contributes to the overall increase in ROS generation and may result in the progression of the cancer.
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1164
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Regulation of mitochondrial oxidative phosphorylation through cell signaling. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2007; 1773:1701-20. [DOI: 10.1016/j.bbamcr.2007.10.001] [Citation(s) in RCA: 191] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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1165
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Abstract
Metabolic component depletion in model systems results in life-span extension, which has been difficult to reconcile with human metabolic pathologies. Recently, Rea et al. (2007) have shown that mitochondrial electron transport chain RNAi phenotypes in the worm C. elegans are dose dependent, providing an alternative view of mitochondrial function in longevity and metabolic diseases.
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Affiliation(s)
- Jenni Durieux
- Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
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1166
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Abstract
The p53 tumor suppressor plays a pivotal role in multicellular organism by enforcing benefits of the organism over those of an individual cell. The task of p53 is to control the integrity and correctness of all processes in each individual cell and in the organism as a whole. Information about the state of ongoing events in the cell is gathered through multiple signaling pathways that convey signals modifying activities of p53. Changes in the activities depend on the character of damages or deviations from optimum in processes, and the activity of p53 changes depending on the degree of the aberration, which results in either stimulation of repair processes and protective mechanisms, or the cessation of further cell divisions and the induction of programmed cell death. The strategy of p53 ensures genetic identity of cells and prevents the selection of abnormal cells. By accomplishing these strategic tasks, p53 may use a wide spectrum of activities, such as its ability to function as a transcription factor, by inducing or repressing different genes, or as an enzyme, by acting as an exonuclease during DNA reparation, or as an adaptor or a regulatory protein, intervening into functions of numerous signaling pathways. Loss of function of the p53 gene occurs in virtually every case of cancer, and deficiency in p53 is an unavoidable prerequisite to the development of malignancies. The functions of p53 play substantial roles in many other pathologies as well as in the aging process. This review is focused on strategies of the p53 gene, demonstrating individual mechanisms underlying its functions.
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Affiliation(s)
- P M Chumakov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia.
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1167
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Banci L, Bertini I, Ciofi-Baffoni S, Gerothanassis IP, Leontari I, Martinelli M, Wang S. A structural characterization of human SCO2. Structure 2007; 15:1132-40. [PMID: 17850752 DOI: 10.1016/j.str.2007.07.011] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2007] [Revised: 07/12/2007] [Accepted: 07/16/2007] [Indexed: 11/19/2022]
Abstract
Human Sco2 is a mitochondrial membrane-bound protein involved in copper supply for the assembly of cytochrome c oxidase in eukaryotes. Its precise action is not yet understood. We report here a structural and dynamic characterization by NMR of the apo and copper(I) forms of the soluble fragment. The structural and metal binding features of human Cu(I)Sco2 are similar to the more often studied Sco1 homolog, although the dynamic properties and the conformational disorder are quite different when the apo forms and the copper(I)-loaded forms of the two proteins are compared separately. Such differences are accounted for in terms of the different physicochemical properties in strategic protein locations. The misfunction of the known pathogenic mutations is discussed on the basis of the obtained structure.
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Affiliation(s)
- Lucia Banci
- Magnetic Resonance Center (CERM) and Department of Chemistry, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Florence, Italy
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1168
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Jones RG, Thompson CB. Revving the engine: signal transduction fuels T cell activation. Immunity 2007; 27:173-8. [PMID: 17723208 DOI: 10.1016/j.immuni.2007.07.008] [Citation(s) in RCA: 274] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2007] [Revised: 07/16/2007] [Accepted: 07/25/2007] [Indexed: 11/30/2022]
Abstract
For initiation of an immune response, resting T cells must reprogram their metabolism. Continuing the "From the Field" series (see Editorial [2007] 26, 131), Jones and Thompson draw attention to the importance of metabolism during T cell activation and consider how this process is regulated by receptor-mediated signal transduction.
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Affiliation(s)
- Russell G Jones
- Abramson Family Cancer Research Institute, Department of Cancer Biology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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1169
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Bertini I, Cavallaro G. Metals in the “omics” world: copper homeostasis and cytochrome c oxidase assembly in a new light. J Biol Inorg Chem 2007; 13:3-14. [DOI: 10.1007/s00775-007-0316-9] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2007] [Accepted: 10/25/2007] [Indexed: 01/20/2023]
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1170
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Bragado P, Armesilla A, Silva A, Porras A. Apoptosis by cisplatin requires p53 mediated p38alpha MAPK activation through ROS generation. Apoptosis 2007; 12:1733-42. [PMID: 17505786 DOI: 10.1007/s10495-007-0082-8] [Citation(s) in RCA: 290] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Cisplatin is one of the major chemotherapeutic weapons used against different human cancers, although its mechanism to induce apoptosis is not fully understood. The presence of wild type p53 has been suggested to be important for cisplatin cytotoxicity, hence we found that cisplatin induced apoptosis in cell lines with functional p53. Using the HCT116 colon carcinoma derived cell line we have established that the apoptotic activity of cisplatin requires the onset of a p53-mediated p38alpha MAPK pathway through generation of reactive oxygen species (ROS). HCT116 p53-deficient cells were much less sensitive to apoptosis by cisplatin than their p53wt counterparts, where apoptosis was strongly inhibited by antioxidants. Moreover, the presence of pifithrin-alpha, an inhibitor of p53 transcriptional activity, blocked cisplatin-induced apoptosis, reduced the generation of ROS produced upon cisplatin treatment. In addition, we have identified p38alpha as the isoform necessary for cisplatin-induced apoptosis, upon activation by p53-mediated ROS production. p38alpha MAPK contributes to further activation of p53, which leads to a positive feedback loop, p38alpha MAPK/p53. We conclude that the p53/ROS/p38alpha MAPK cascade is essential for cisplatin-induced cell death in HCT116 cells and the subsequent p38alpha/p53 positive feedback loop strongly enhances the initial p53 activation.
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Affiliation(s)
- Paloma Bragado
- Centro de Investigaciones Biológicas, CSIC, 28040 Madrid, Spain
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1171
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Jayadev S, Yun B, Nguyen H, Yokoo H, Morrison RS, Garden GA. The glial response to CNS HIV infection includes p53 activation and increased expression of p53 target genes. J Neuroimmune Pharmacol 2007; 2:359-70. [PMID: 18040854 DOI: 10.1007/s11481-007-9095-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2007] [Accepted: 09/26/2007] [Indexed: 01/02/2023]
Abstract
HIV-associated dementia (HAD) is a chronic neuroinflammatory disease that remains an important clinical problem without available rational treatment. As HIV does not infect neurons, the pathogenesis of HAD is thought to be secondary to the impact of infected leukocytes, including parenchymal microglia, which can secrete inflammatory mediators and viral products that alter the function of surrounding uninfected cells. We previously reported that the transcription factor p53 accumulates in neurons, microglia, and astrocytes of HAD patients. We have also shown that microglia from p53-deficient mice fail to induce neurotoxicity in response to the HIV coat protein gp120 in a coculture system, supporting the hypothesis that p53 plays a pathogenic role in the chronic neuroinflammatory component of HIV-associated neurodegeneration. We analyzed the extent and cell type specificity of p53 accumulation in subcortical white matter of ten AIDS patients that had previously been shown to demonstrate white matter p53 accumulation. To determine if p53 activation functioned to alter gene expression in HAD, cortical tissue sections were also immunolabeled for the p53 target genes Bax and p21(WAF1). These studies reveal that microglia, astrocytes, and oligodendrocytes all demonstrate p53 activation in response to HIV infection. We observed immunoreactivity for both Bax and p21(WAF1) in neurons and glia from patients demonstrating elevated p53 immunoreactivity. Our findings demonstrate that widespread increased p53 expression is present in HAD. Activation of p53 mediated pathways in the glia of HAD patients may contribute to the neuroinflammatory processes that promote neurodegeneration by inhibiting glial proliferation and/or promoting glial cell dysfunction.
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Affiliation(s)
- Suman Jayadev
- Department of Neurology, University of Washington, Seattle, WA, USA
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1172
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Abstract
The evolution of biological complexity beyond single-celled organisms was linked temporally with the development of an oxygen atmosphere. Functionally, this linkage can be attributed to oxygen ranking high in both abundance and electronegativity amongst the stable elements of the universe. That is, reduction of oxygen provides for close to the largest possible transfer of energy for each electron transfer reaction. This suggests the general hypothesis that the steep thermodynamic gradient of an oxygen environment was permissive for the development of multicellular complexity. A corollary of this hypothesis is that aerobic metabolism underwrites complex biological function mechanistically at all levels of organization. The strong contemporary functional association of aerobic metabolism with both physical capacity and health is presumably a product of the integral role of oxygen in our evolutionary history. Here we provide arguments from thermodynamics, evolution, metabolic network analysis, clinical observations and animal models that are in accord with the centrality of oxygen in biology.
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Affiliation(s)
- Lauren G Koch
- Functional Genomics Laboratory, Department of Physical Medicine and Rehabilitation, University of Michigan, Ann Arbor, MI 48109-2200, USA
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1173
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Chandrakanthan V, Chami O, Stojanov T, O'Neill C. Variable expressivity of the tumour suppressor protein TRP53 in cryopreserved human blastocysts. Reprod Biol Endocrinol 2007; 5:39. [PMID: 17939878 PMCID: PMC2099431 DOI: 10.1186/1477-7827-5-39] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2007] [Accepted: 10/17/2007] [Indexed: 12/16/2022] Open
Abstract
In a mouse model, in vitro fertilization or extended embryo culture leads to the increased expression of TRP53 in susceptible embryos. Ablation of the TRP53 gene improved embryo viability indicating that increased expression of TRP53 is a cause of the reduction of embryo viability resulting from in vitro fertilization or embryo culture. This study investigates the status of TRP53 expression in human embryos produced by intracytoplasmic sperm injection. Following fertilization, embryos were cultured for 96 h and then cryopreserved. Immediately upon thawing they were fixed in formaldehyde and subjected to immunostaining for TRP53. Staining was visualized by confocal microscopy. Negative controls were incubated with isotype control immunoglobulin and showed negligible staining. All embryos showed TRP53 staining above negative controls. TRP53 staining was heterogenous within and between embryos. An embryo that showed retarded development showed high levels of TRP53 expression. A blastocyst that had a collapsed blastocoel also showed high levels of TRP53 compared to morphologically normal blastocysts. Most TRP53 staining was in the region of the nucleus. Morphologically normal blastocysts tended to show little nuclear accumulation of stain. However, some cells within these embryos had high levels of nuclear TRP53 expression. The results show that embryos have varying sensitivity to the stresses of production and culture in vitro, and this resulted in variable expressivity of TRP53.
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Affiliation(s)
- Vashe Chandrakanthan
- Human Reproduction Unit, Royal North Shore Hospital, St Leonards, NSW, 2065, Australia and the Discipline of Physiology, University of Sydney, Sydney, NSW, Australia
| | - Omar Chami
- Sydney IVF, 321 Kent St. Sydney, NSW, Australia
| | | | - Chris O'Neill
- Human Reproduction Unit, Royal North Shore Hospital, St Leonards, NSW, 2065, Australia and the Discipline of Physiology, University of Sydney, Sydney, NSW, Australia
- Discipline of Medicine, University of Sydney, Sydney, NSW, Australia
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1174
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Rodier F, Campisi J, Bhaumik D. Two faces of p53: aging and tumor suppression. Nucleic Acids Res 2007; 35:7475-84. [PMID: 17942417 PMCID: PMC2190721 DOI: 10.1093/nar/gkm744] [Citation(s) in RCA: 269] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2007] [Revised: 09/05/2007] [Accepted: 09/05/2007] [Indexed: 01/03/2023] Open
Abstract
The p53 tumor suppressor protein, often termed guardian of the genome, integrates diverse physiological signals in mammalian cells. In response to stress signals, perhaps the best studied of which is the response to DNA damage, p53 becomes functionally active and triggers either a transient cell cycle arrest, cell death (apoptosis) or permanent cell cycle arrest (cellular senescence). Both apoptosis and cellular senescence are potent tumor suppressor mechanisms that irreversibly prevent damaged cells from undergoing neoplastic transformation. However, both processes can also deplete renewable tissues of proliferation-competent progenitor or stem cells. Such depletion, in turn, can compromise the structure and function of tissues, which is a hallmark of aging. Moreover, whereas apoptotic cells are by definition eliminated from tissues, senescent cells can persist, acquire altered functions, and thus alter tissue microenvironments in ways that can promote both cancer and aging phenotypes. Recent evidence suggests that increased p53 activity can, at least under some circumstances, promote organismal aging. Here, we discuss the role of p53 as a key regulator of the DNA damage responses, and discuss how p53 integrates the outcome of the DNA damage response to optimally balance tumor suppression and longevity.
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Affiliation(s)
- Francis Rodier
- Buck Institute for Age Research, 8001 Redwood Boulevard, Novato, CA 94945 and Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Judith Campisi
- Buck Institute for Age Research, 8001 Redwood Boulevard, Novato, CA 94945 and Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Dipa Bhaumik
- Buck Institute for Age Research, 8001 Redwood Boulevard, Novato, CA 94945 and Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
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1175
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Alvarado-Vásquez N, Zapata E, Alcázar-Leyva S, Massó F, Montaño LF. Reduced NO synthesis and eNOS mRNA expression in endothelial cells from newborns with a strong family history of type 2 diabetes. Diabetes Metab Res Rev 2007; 23:559-66. [PMID: 17385193 DOI: 10.1002/dmrr.743] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
BACKGROUND A deficient synthesis of nitric oxide (NO) may play a role in the early endothelial dysfunction of healthy humans with a strong family history of type 2 diabetes (DM2). In this study, we evaluate the intracellular synthesis of NO and the expression of eNOS transcripts in human umbilical vein endothelial cells (HUVECs), exposed to high glucose concentrations, of healthy newborns with (experimental) and without (control) a strong family history of DM2. METHODS HUVECs were incubated in M-199 culture media (containing a 5 mmol/L physiological glucose concentration) or supraphysiological glucose concentrations (15 or 30 mmol/L), for 48 h. Flow cytometry, reactive of Griess and RT-PCR were used to determine intracellular NO synthesis, presence of NO metabolites, and expression of eNOS, GLUT1 or p53 transcripts. RESULTS NO synthesis in experimental HUVECs showed a progressive reduction in the presence of increasing glucose concentration (11% for 5 mmol to 8% for 30 mmol; p < 0.01), whereas control HUVECs showed an increase in NO synthesis (3% for 5 mmol to 31% for 30 mmol; p < 0.001). In experimental HUVECs, we found a diminished expression of eNOS and p53, and also an enhanced expression of GLUT1 mRNA transcripts. Control HUVECs showed an increase in eNOS, and no modifications in p53 or GLUT1 mRNA transcripts. CONCLUSIONS Our results show how HUVECs, isolated from healthy newborns with a strong family history of DM2, have an abnormal intracellular synthesis of NO and an impaired expression of eNOS, GLUT1 and p53 genes, all associated with NO synthesis.
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Affiliation(s)
- Noé Alvarado-Vásquez
- Departamento de Bioquímica, Instituto Nacional de Enfermedades Respiratorias, México.
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1176
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López-Ríos F, Sánchez-Aragó M, García-García E, Ortega AD, Berrendero JR, Pozo-Rodríguez F, López-Encuentra A, Ballestín C, Cuezva JM. Loss of the Mitochondrial Bioenergetic Capacity Underlies the Glucose Avidity of Carcinomas. Cancer Res 2007; 67:9013-7. [PMID: 17909002 DOI: 10.1158/0008-5472.can-07-1678] [Citation(s) in RCA: 144] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The down-regulation of the catalytic subunit of the mitochondrial H+-ATP synthase (beta-F1-ATPase) is a hallmark of most human carcinomas. This characteristic of the cancer cell provides a proteomic signature of cellular bioenergetics that can predict the prognosis of colon, lung, and breast cancer patients. Here we show that the in vivo tumor glucose uptake of lung carcinomas, as assessed by positron emission tomography in 110 patients using 2-deoxy-2-[18F]fluoro-d-glucose as probe, inversely correlates with the bioenergetic signature determined by immunohistochemical analysis in tumor surgical specimens. Further, we show that inhibition of the activity of oxidative phosphorylation by incubation of cancer cells with oligomycin triggers a rapid increase in their rates of aerobic glycolysis. Moreover, we show that the cellular expression level of the beta-F1-ATPase protein of mitochondrial oxidative phosphorylation inversely correlates (P < 0.001) with the rates of aerobic glycolysis in cancer cells. The results highlight the relevance of the alteration of the bioenergetic function of mitochondria for glucose capture and consumption by aerobic glycolysis in carcinomas.
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Affiliation(s)
- Fernando López-Ríos
- Hospital Universitario 12 de Octubre, CIBER de Enfermedades Respiratorias, Universidad Autónoma de Madrid-Consejo Superior de Investigaciones Cientificas, Madrid, Spain
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1177
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Dai C, Whitesell L, Rogers AB, Lindquist S. Heat shock factor 1 is a powerful multifaceted modifier of carcinogenesis. Cell 2007; 130:1005-18. [PMID: 17889646 PMCID: PMC2586609 DOI: 10.1016/j.cell.2007.07.020] [Citation(s) in RCA: 632] [Impact Index Per Article: 37.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2007] [Revised: 06/11/2007] [Accepted: 07/13/2007] [Indexed: 11/15/2022]
Abstract
Heat shock factor 1 (HSF1) is the master regulator of the heat shock response in eukaryotes, a very highly conserved protective mechanism. HSF1 function increases survival under a great many pathophysiological conditions. How it might be involved in malignancy remains largely unexplored. We report that eliminating HSF1 protects mice from tumors induced by mutations of the RAS oncogene or a hot spot mutation in the tumor suppressor p53. In cell culture, HSF1 supports malignant transformation by orchestrating a network of core cellular functions including proliferation, survival, protein synthesis, and glucose metabolism. The striking effects of HSF1 on oncogenic transformation are not limited to mouse systems or tumor initiation; human cancer lines of diverse origins show much greater dependence on HSF1 function to maintain proliferation and survival than their nontransformed counterparts. While it enhances organismal survival and longevity under most circumstances, HSF1 has the opposite effect in supporting the lethal phenomenon of cancer.
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MESH Headings
- 9,10-Dimethyl-1,2-benzanthracene
- Animals
- Carcinogens
- Cell Line, Tumor
- Cell Proliferation
- Cell Survival
- Cell Transformation, Neoplastic/genetics
- Cell Transformation, Neoplastic/metabolism
- Cell Transformation, Neoplastic/pathology
- DNA-Binding Proteins/deficiency
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- Fibroblasts/metabolism
- Fibroblasts/pathology
- Gene Expression Regulation, Neoplastic
- Genotype
- Glucose/metabolism
- Heat Shock Transcription Factors
- Humans
- Methylnitronitrosoguanidine
- Mice
- Mice, Inbred BALB C
- Mice, Knockout
- Mutation
- Phenotype
- Protein Biosynthesis
- Proto-Oncogene Proteins c-sis/genetics
- Proto-Oncogene Proteins c-sis/metabolism
- RNA Interference
- RNA, Small Interfering/metabolism
- Signal Transduction/genetics
- Skin/metabolism
- Skin/pathology
- Skin Neoplasms/chemically induced
- Skin Neoplasms/genetics
- Skin Neoplasms/metabolism
- Skin Neoplasms/pathology
- Tetradecanoylphorbol Acetate
- Time Factors
- Transcription Factors/deficiency
- Transcription Factors/genetics
- Transcription Factors/metabolism
- Transduction, Genetic
- Tumor Suppressor Protein p53/genetics
- Tumor Suppressor Protein p53/metabolism
- ras Proteins/genetics
- ras Proteins/metabolism
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Affiliation(s)
- Chengkai Dai
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Luke Whitesell
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Arlin B. Rogers
- Divison of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Susan Lindquist
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
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1178
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Abstract
Mitochondria cannot be made de novo but replicate by a mechanism of recruitment of new proteins, which are added to preexisting subcompartments. Although mitochondria have their own DNA, more than 98% of the total protein complement of the organelle is encoded by the nuclear genome. Mitochondrial biogenesis requires a coordination of expression of two genomes and therefore cross talk between the nucleus and mitochondria. In mammals, regulation of mitochondrial biogenesis and proliferation is influenced by external factors, such as nutrients, hormones, temperature, exercise, hypoxia, and aging. This complexity points to the existence of a coordinated and tightly regulated network connecting different pathways. Communications are also required for eliciting mitochondrial responses to specific stress pathways. This review covers the mechanisms of mitochondrial biogenesis and the way cells respond to external signals to maintain mitochondrial function and cellular homeostasis.
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Affiliation(s)
- Michael T Ryan
- Department of Biochemistry, La Trobe University, Melbourne 3086, Australia.
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1179
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Abstract
Rapidly growing tumors invariably contain hypoxic regions. Adaptive response to hypoxia through angiogenesis, enhanced glucose metabolism and diminished but optimized mitochondrial respiration confers survival and growth advantage to hypoxic tumor cells. In this review, the roles of hypoxia, the hypoxia inducible factors, oncogenes and tumor suppressors in metabolic adaptation of tumors are discussed. These new insights into hypoxic metabolic alterations in tumors will hopefully lead us to target tumor bioenergetics for the treatment of cancers.
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Affiliation(s)
- Jung-whan Kim
- Division of Hematology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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1180
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Hagland H, Nikolaisen J, Hodneland LI, Gjertsen BT, Bruserud Ø, Tronstad KJ. Targeting mitochondria in the treatment of human cancer: a coordinated attack against cancer cell energy metabolism and signalling. Expert Opin Ther Targets 2007; 11:1055-69. [PMID: 17665978 DOI: 10.1517/14728222.11.8.1055] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Mitochondria have major roles in bioenergetics and vital signalling of the mammalian cell. Consequently, these organelles have been implicated in the process of carcinogenesis, which includes alterations of cellular metabolism and cell death pathways. Multiple molecular routes of malignant transformation appear to result in the common ability of many tumours to take up large amounts of glucose. This metabolic twist has been explained by phenomena such as aerobic glycolysis and impaired mitochondrial function, and is linked to tumour growth potential via major cellular signalling pathways. This paper reviews the literature on central mechanisms through which energy metabolism merges with growth, proliferation and death signalling, which tend to include mitochondria at some level. These processes can potentially be targeted by pharmacological agents for therapeutic and chemosensitising purposes.
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Affiliation(s)
- Hanne Hagland
- University of Bergen, Department of Biomedicine, Bergen, Norway.
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1181
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Gieldon A, Mori M, Del Conte R. Theoretical study on binding of S100B protein. J Mol Model 2007; 13:1123-31. [PMID: 17713798 DOI: 10.1007/s00894-007-0231-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2007] [Accepted: 06/29/2007] [Indexed: 11/27/2022]
Abstract
S100B protein is one of the factors involved in the down-regulation of tumor suppressor protein p53, a transcription activator that signals for cycle arrest and apoptosis. As the inactivation of normal p53 functions is found in over half of human cancers, restoration of normal p53 functions through the destruction or prevention of S100B--p53 complexes represents a possible approach for the development of anti-cancer drugs. The aim of this work was to propose the S100B binding interface through an examination of the literature and use of molecular modeling (MM) techniques with AutoDock program and the AMBER force field. We propose two residues in the S100B binding pocket (Val56, Phe76) and two residues on the protein surface (Val52, Ala83) are essential for ligand binding. The data presented here indicate that interactions with these four residues are necessary for a reduction in the incidence of the S100B--p53 complex. Additionally, we have tried to explain a mechanism for the action of pentamidine, the best-known S100B ligand, and have proposed two S100B--pentamidine structures. The results presented here may be useful for the efficient design of new S100B ligands.
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Affiliation(s)
- Artur Gieldon
- Protera S. r. l., Viale delle Idee, 22, 50019, Sesto Fiorentino, Fi, Italy.
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1182
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Cuezva JM, Sánchez-Aragó M, Sala S, Blanco-Rivero A, Ortega AD. A message emerging from development: the repression of mitochondrial β-F1-ATPase expression in cancer. J Bioenerg Biomembr 2007; 39:259-65. [PMID: 17712532 DOI: 10.1007/s10863-007-9087-9] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Mitochondrial research has experienced a considerable boost during the last decade because organelle malfunctioning is in the genesis and/or progression of a vast array of human pathologies including cancer. The renaissance of mitochondria in the cancer field has been promoted by two main facts: (1) the molecular and functional integration of mitochondrial bioenergetics with the execution of cell death and (2) the implementation of (18)FDG-PET for imaging and staging of tumors in clinical practice. The latter, represents the bed-side translational development of the metabolic hallmark that describes the bioenergetic phenotype of most cancer cells as originally predicted at the beginning of previous century by Otto Warburg. In this minireview we will briefly summarize how the study of energy metabolism during liver development forced our encounter with Warburg's postulates and prompted us to study the mechanisms that regulate the biogenesis of mitochondria in the cancer cell.
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Affiliation(s)
- José M Cuezva
- Departamento de Biología Molecular, Centro de Biología Molecular "Severo Ochoa", Centro de Investigación Biomédica en Red de Enfermedades Raras, Universidad Autónoma de Madrid, 28049. Madrid, Spain.
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1183
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Buzzai M, Jones RG, Amaravadi RK, Lum JJ, DeBerardinis RJ, Zhao F, Viollet B, Thompson CB. Systemic treatment with the antidiabetic drug metformin selectively impairs p53-deficient tumor cell growth. Cancer Res 2007; 67:6745-52. [PMID: 17638885 DOI: 10.1158/0008-5472.can-06-4447] [Citation(s) in RCA: 704] [Impact Index Per Article: 41.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The effect of the antidiabetic drug metformin on tumor growth was investigated using the paired isogenic colon cancer cell lines HCT116 p53(+/+) and HCT116 p53(-/-). Treatment with metformin selectively suppressed the tumor growth of HCT116 p53(-/-) xenografts. Following treatment with metformin, we detected increased apoptosis in p53(-/-) tumor sections and an enhanced susceptibility of p53(-/-) cells to undergo apoptosis in vitro when subject to nutrient deprivation. Metformin is proposed to function in diabetes treatment as an indirect activator of AMP-activated protein kinase (AMPK). Treatment with AICAR, another AMPK activator, also showed a selective ability to inhibit p53(-/-) tumor growth in vivo. In the presence of either of the two drugs, HCT116 p53(+/+) cells, but not HCT116 p53(-/-) cells, activated autophagy. A similar p53-dependent induction of autophagy was observed when nontransformed mouse embryo fibroblasts were treated. Treatment with either metformin or AICAR also led to enhanced fatty acid beta-oxidation in p53(+/+) MEFs, but not in p53(-/-) MEFs. However, the magnitude of induction was significantly lower in metformin-treated cells, as metformin treatment also suppressed mitochondrial electron transport. Metformin-treated cells compensated for this suppression of oxidative phosphorylation by increasing their rate of glycolysis in a p53-dependent manner. Together, these data suggest that metformin treatment forces a metabolic conversion that p53(-/-) cells are unable to execute. Thus, metformin is selectively toxic to p53-deficient cells and provides a potential mechanism for the reduced incidence of tumors observed in patients being treated with metformin.
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Affiliation(s)
- Monica Buzzai
- Abramson Family Cancer Research Institute, Department of Cancer Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
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1184
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Provent P, Benito M, Hiba B, Farion R, López-Larrubia P, Ballesteros P, Rémy C, Segebarth C, Cerdán S, Coles JA, García-Martín ML. Serial In vivo Spectroscopic Nuclear Magnetic Resonance Imaging of Lactate and Extracellular pH in Rat Gliomas Shows Redistribution of Protons Away from Sites of Glycolysis. Cancer Res 2007; 67:7638-45. [PMID: 17699768 DOI: 10.1158/0008-5472.can-06-3459] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
The acidity of the tumor microenvironment aids tumor growth, and mechanisms causing it are targets for potential therapies. We have imaged extracellular pH (pHe) in C6 cell gliomas in rat brain using 1H magnetic resonance spectroscopy in vivo. We used a new probe molecule, ISUCA [(±)2-(imidazol-1-yl)succinic acid], and fast imaging techniques, with spiral acquisition in k-space. We obtained a map of metabolites [136 ms echo time (TE)] and then infused ISUCA in a femoral vein (25 mmol/kg body weight over 110 min) and obtained two consecutive images of pHe within the tumor (40 ms TE, each acquisition taking 25 min). pHe (where ISUCA was present) ranged from 6.5 to 7.5 in voxels of 0.75 μL and did not change detectably when [ISUCA] increased. Infusion of glucose (0.2 mmol/kg·min) decreased tumor pHe by, on average, 0.150 (SE, 0.007; P < 0.0001, 524 voxels in four rats) and increased the mean area of measurable lactate peaks by 54.4 ± 3.4% (P < 0.0001, 287 voxels). However, voxel-by-voxel analysis showed that, both before and during glucose infusion, the distributions of lactate and extracellular acidity were very different. In tumor voxels where both could be measured, the glucose-induced increase in lactate showed no spatial correlation with the decrease in pHe. We suggest that, although glycolysis is the main source of protons, distributed sites of proton influx and efflux cause pHe to be acidic at sites remote from lactate production. [Cancer Res 2007;67(16):7638–45]
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Affiliation(s)
- Peggy Provent
- Institut National de la Santé et de la Recherche Médicale, U836, France
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1185
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Abstract
At a molecular level, hypoxia induces the stabilization and activation of the α-subunit of an α/β heterodimeric transcription factor, appropriately termed HIF (hypoxia-inducible factor). Hypoxia is encountered, in particular, in tumour tissues, as a result of an insufficient and defective vasculature present in a highly proliferative tumour mass. In this context the active HIF heterodimer binds to and induces a panel of genes that lead to modification in a vast range of cellular functions that allow cancer cells to not only survive but to continue to proliferate and metastasize. Therefore HIF plays a key role in tumorigenesis, tumour development and metastasis, and its expression in solid tumours is associated with a poor patient outcome. Among the many genes induced by HIF are genes responsible for glucose transport and glucose metabolism. The products of these genes allow cells to adapt to cycles of hypoxic stress by maintaining a level of ATP sufficient for survival and proliferation. Whereas normal cells metabolize glucose through a cytoplasmic- and mitochondrial-dependent pathway, cancer cells preferentially use a cytoplasmic, glycolytic pathway that leads to an increased acid load due, in part, to the high level of production of lactic acid. This metabolic predilection of cancer cells is primarily dependent directly on the HIF activity but also indirectly through changes in the activity of tumour suppressors and oncogenes. A better understanding of HIF-dependent metabolism and pH regulation in cancer cells should lead to further development of diagnostic tools and novel therapeutics that will bring benefit to cancer patients.
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Affiliation(s)
- M Christiane Brahimi-Horn
- Institute of Signaling, Developmental Biology and Cancer Research, CNRS UMR 6543, University of Nice, Centre A. Lacassagne, 33 Avenue Valombrose, 06189 Nice, France.
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1186
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Kinzler I, Haseroth E, Hauser C, Rück A. Role of mitochondria in cell death induced by Photofrin-PDT and ursodeoxycholic acid by means of SLIM. Photochem Photobiol Sci 2007; 6:1332-40. [PMID: 18046490 DOI: 10.1039/b705919a] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The present study was undertaken to find new ways to improve efficacy of photodynamic therapy (PDT). We investigated the combinatory effect of the photosensitizer Photofrin and ursodeoxycholic acid (UDCA). UDCA is a relatively non-toxic bile acid which is used inter alia as a treatment for cholestatic disorders and was reported to enhance PDT efficiency of two other photosensitizers. Since besides necrosis and autophagic processes apoptosis has been found to be a prominent form of cell death in response to PDT for many cells in culture, several appropriate tests, such as cytochrome c release, caspase activation and DNA fragmentation were performed. Furthermore spectral resolved fluorescence lifetime imaging (SLIM) was used to analyse the cellular composition of Photofrin and the status of the enzymes of the respiratory chain. Our experiments with two human hepatoblastoma cell lines revealed that the combination of Photofrin with UDCA significantly enhanced efficacy of PDT for both cell lines even though the underlying molecular mechanism for the mode of action of Photofrin seems to be different to some extent. In HepG2 cells cell death was clearly the consequence of mitochondrial disturbance as shown by cytochrome c release and DNA fragmentation, whereas in Huh7 cells these features were not observed. Other mechanisms seem to be more important in this case. One reason for the enhanced PDT effect when UDCA is also applied could be that UDCA destabilizes the mitochondrial membrane. This could be concluded from the fluorescence lifetime of the respiratory chain enzymes which turned out to be longer in the presence of UDCA in HepG2 cells, suggesting a perturbation of the mitochondrial membrane. The threshold at which PDT damages the mitochondrial membrane was therefore lower and correlated with the enhanced cytochrome c release observed post PDT. Thus enforced photodamage leads to a higher loss of cell viability.
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Affiliation(s)
- Ingrid Kinzler
- Institute for Lasertechnologies (ILM), Helmholtzstrasse 12, D-89081, Ulm
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1187
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Abstract
At first glance, cancer and ageing would seem to be unlikely bedfellows. Yet the origins for this improbable union can actually be traced back to a sequence of tragic--and some say unethical--events that unfolded more than half a century ago. Here we review the series of key observations that has led to a complex but growing convergence between our understanding of the biology of ageing and the mechanisms that underlie cancer.
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Affiliation(s)
- Toren Finkel
- Cardiology Branch, NIH, NHLBI, Building 10/CRC 5-3330, 10 Center Drive, Bethesda, Maryland 20892, USA.
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1188
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Godinot C, de Laplanche E, Hervouet E, Simonnet H. Actuality of Warburg’s views in our understanding of renal cancer metabolism. J Bioenerg Biomembr 2007; 39:235-41. [PMID: 17665292 DOI: 10.1007/s10863-007-9088-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
More than 50 years ago, Warburg proposed that the shift in glucose metabolism from oxidative phosphorylation (OXPHOS) to glycolysis occurring in spite of an adequate oxygen supply was at the root of cancer. This hypothesis often disregarded over the following years has recently stirred up much interest due to progress made in cancer genetics and proteomics. Studies related to renal cancers have been particularly informative to understand how abnormal use of glucose and decrease in OXPHOS are linked to cell proliferation in tumors. Indeed, in aggressive tumors such as clear cell renal carcinoma, the von Hippel-Lindau factor invalidation stabilizes the hypoxia-inducible factor (HIF) in the presence of oxygen. HIF stimulating glycolytic gene expression increases the glycolytic flux. Deficiencies in genes involved in oxidative phosphorylation that can explain the down-regulation of OXPHOS components also begin to be identified. These findings are important in the search for novel therapeutic approaches to cancer treatment.
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Affiliation(s)
- Catherine Godinot
- Center of Molecular and Cellular Genetics (CGMC), UMR 5534, CNRS, University Claude Bernard of Lyon 1, 69622 Villeurbanne, France.
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1189
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López-Lázaro M. Digitoxin as an anticancer agent with selectivity for cancer cells: possible mechanisms involved. Expert Opin Ther Targets 2007; 11:1043-53. [PMID: 17665977 DOI: 10.1517/14728222.11.8.1043] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Accumulating preclinical and clinical data suggest that the cardiac drug digitoxin might be used in cancer therapy. Recent reports have shown that digitoxin can inhibit the growth and induce apoptosis in cancer cells at concentrations commonly found in the plasma of cardiac patients treated with this drug. Several mechanisms have been associated with the anticancer activity of digitoxin, yet at present it is unknown why malignant cells are more susceptible to this cardiac glycoside than non-malignant cells. This report analyses the possible anticancer mechanisms of digitoxin and proposes that the inhibition of glycolysis may be a key mechanism by which this natural product selectively targets cancer cells. Finally, whether or not there is enough evidence to support the clinical evaluation of digitoxin in patients with cancer is discussed.
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Affiliation(s)
- Miguel López-Lázaro
- University of Seville, Department of Pharmacology, Faculty of Pharmacy, Sevilla, Spain.
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1190
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van der Horst A, Burgering BMT. Stressing the role of FoxO proteins in lifespan and disease. Nat Rev Mol Cell Biol 2007; 8:440-50. [PMID: 17522590 DOI: 10.1038/nrm2190] [Citation(s) in RCA: 565] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Members of the class O of forkhead box transcription factors (FoxO) have important roles in metabolism, cellular proliferation, stress tolerance and probably lifespan. The activity of FoxOs is tightly regulated by post-translational modifications, including phosphorylation, acetylation and ubiquitylation. Several of the enzymes that regulate the turnover of these post-translational modifications are shared between FoxO and p53. These regulatory enzymes affect FoxO and p53 function in an opposite manner. This shared yet opposing regulatory network between FoxOs and p53 may underlie a 'trade-off' between disease and lifespan.
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Affiliation(s)
- Armando van der Horst
- Department of Physiological Chemistry, Centre for Biomedical Genetics, University Medical Center Utrecht, 3584 CG Utrecht, The Netherlands
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1191
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Manoli I, Alesci S, Blackman MR, Su YA, Rennert OM, Chrousos GP. Mitochondria as key components of the stress response. Trends Endocrinol Metab 2007; 18:190-8. [PMID: 17500006 DOI: 10.1016/j.tem.2007.04.004] [Citation(s) in RCA: 248] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2007] [Revised: 04/02/2007] [Accepted: 04/30/2007] [Indexed: 02/09/2023]
Abstract
The exquisitely orchestrated adaptive response to stressors that challenge the homeostasis of the cell and organism involves important changes in mitochondrial function. A complex signaling network enables mitochondria to sense internal milieu or environmental changes and to adjust their bioenergetic, thermogenic, oxidative and/or apoptotic responses accordingly, aiming at re-establishment of homeostasis. Mitochondrial dysfunction is increasingly recognized as a key component in both acute and chronic allostatic states, although the extent of its role in the pathogenesis of such conditions remains controversial. Genetic and environmental factors that determine mitochondrial function might contribute to the significant variation of the stress response. Understanding the often reciprocal interplay between stress mediators and mitochondrial function is likely to help identify potential therapeutic targets for many stress and mitochondria-related pathologies.
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Affiliation(s)
- Irini Manoli
- Human Biochemical Genetics Section, MGB, NHGRI, NIH, Bethesda, MD 20892, USA.
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1192
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Abstract
As a component of the response to acute stress, p53 has a well established role in protecting against cancer development. However, it is now becoming clear that p53 can have a much broader role and can contribute to the development, life expectancy and overall fitness of an organism. Although the function of p53 as a tumour suppressor ensures that we can't live without it, an integrated view of p53 suggests that not all of its functions are conducive to a long and healthy life.
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Affiliation(s)
- Karen H Vousden
- Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK.
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1193
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Brahimi-Horn MC, Pouysségur J. Oxygen, a source of life and stress. FEBS Lett 2007; 581:3582-91. [PMID: 17586500 DOI: 10.1016/j.febslet.2007.06.018] [Citation(s) in RCA: 253] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2007] [Revised: 06/04/2007] [Accepted: 06/10/2007] [Indexed: 12/30/2022]
Abstract
Oxygen is an essential element in the survival of complex organisms, however the level of oxygen, low or high, can be a source of stress depending on the biological context. Low levels of oxygen in tissues (hypoxia) can be the consequence of a number of pathophysiological conditions including ischemic disorders and cancer while relative, higher levels (hyperoxia) can lead to retinopathy of prematurity. The local oxygen environment and oxygen consumption dictate vascular homeostasis, vaso-proliferation and vaso-cessation, which is deregulated in these diseases through oxygen-dependent growth factors. In this review, we will introduce aspects of the physiology and biology of oxygen partial pressure and the molecular mechanisms implicated in oxygen sensing. We will outline the regulation and function of the key operator in cellular signalling of hypoxia, the transcription factor, hypoxia-inducible factor. In addition, we will focus on cancer cell hypoxia and on its role in driving cell metabolism, pH regulation and survival.
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Affiliation(s)
- M Christiane Brahimi-Horn
- Institute of Signaling, Developmental Biology and Cancer Research, University of Nice, CNRS UMR 6543, Centre A. Lacassagne, 33 Avenue Valombrose, 06189 Nice, France.
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1194
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Chen Z, Lu W, Garcia-Prieto C, Huang P. The Warburg effect and its cancer therapeutic implications. J Bioenerg Biomembr 2007; 39:267-74. [PMID: 17551814 DOI: 10.1007/s10863-007-9086-x] [Citation(s) in RCA: 228] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Increased aerobic glycolysis in cancer, a phenomenon known as the Warburg effect, has been observed in various tumor cells and represents a major biochemical alteration associated with malignant transformation. Although the exact molecular mechanisms underlying this metabolic change remain to be elucidated, the profound biochemical alteration in cancer cell energy metabolism provides exciting opportunities for the development of therapeutic strategies to preferentially kill cancer cells by targeting the glycolytic pathway. Several small molecules capable of inhibiting glycolysis in experimental systems have been shown to have promising anticancer activity in vitro and in vivo. This review article provides a brief summary of our current understanding of the Warburg effect, the underlying mechanisms, and its influence on the development of therapeutic strategies for cancer treatment.
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Affiliation(s)
- Zhao Chen
- Department of Molecular Pathology, The University of Texas MD Anderson Cancer Center, 7435 Fannin Street, Houston, TX 77030, USA
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1195
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1196
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Koiri RK, Trigun SK, Dubey SK, Singh S, Mishra L. Metal Cu(II) and Zn(II) bipyridyls as inhibitors of lactate dehydrogenase. Biometals 2007; 21:117-26. [PMID: 17541766 DOI: 10.1007/s10534-007-9098-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2007] [Accepted: 04/24/2007] [Indexed: 11/26/2022]
Abstract
Metal complex-protein interaction is an evolving concept for determining cellular targets of metallodrugs. Lacatate dehydrogenase (LDH) is critically implicated in tumor growth and therefore, considered to be an important target protein for anti-tumor metal complexes. Due to efficient biocompatibility of copper (Cu(2+)) and zinc (Zn(2+)), we synthesized CubpyAc(2) . H(2)O (Cu-bpy) and ZnbpyAc(2) . H(2)O (Zn-bpy; where bpy = 2,2' bipyridine, Ac = CH(3)COO(-)) complexes and evaluated their interaction with and modulation of LDH in mouse tissues. The increasing concentration of both the complexes showed a significant shift in UV-Vis spectra of LDH. The binding constant data (Kc = 1 x 10(3) M(-1) for Cu-bpy and 7 x 10(6) M(-1) for Zn-bpy) suggested that Zn-bpy-LDH interaction is stronger than that of Cu-bpy-LDH. LDH modulating potential of the complexes were monitored by perfusing the mice tissues with non-toxic doses of Cu-bpy and Zn-bpy followed by activity measurement and analysis of LDH isozymes on non-denaturing polyacrylamide gel electrophoresis (PAGE). As compared to the control sets, Cu-bpy caused a significant decline (P < 0.05-0.001) in the activity of LDH in all the tissues studied. However, Zn-bpy showed inhibition of LDH only in liver (P < 0.01), kidney (P < 0.001) and heart (P < 0.01), but with no effect in spleen, brain and skeletal muscle tissues. PAGE analysis suggested that all the five LDH isozymes are equally sensitive to both the complexes in the respective tissues. The results suggest that Cu- and Zn-bpy are able to interact with and inhibit LDH, a tumor growth supportive target protein at tissue level.
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Affiliation(s)
- Raj Kumar Koiri
- Biochemistry & Molecular Biology Section, Centre of Advanced Studies in Zoology, Banaras Hindu University, Varanasi, India
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1197
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Alexander BM, Van Kirk EA, Naughton LMA, Murdoch WJ. Ovarian morphometrics in TP53-deficient mice. Anat Rec (Hoboken) 2007; 290:59-64. [PMID: 17441198 PMCID: PMC2571076 DOI: 10.1002/ar.20409] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The objective of these investigations was to characterize ovarian responses to hormonal stimulation in TP53-deficient mice. TP53-deficient (KO) and wild-type (WT) mice were induced to ovulate with pregnant mare serum gonadotropin followed by human chorionic gonadotropin. Effect of estradiol on ovarian morphology was determined in induced and control mice implanted with estradiol-containing or placebo pellets. Blood was collected and mice were killed 7 days following implantation. Preserved ovaries were serially sectioned and stained. Numbers of follicles (all classifications) decreased with ovulation induction, but did not differ between WT and KO mice. Numbers of corpora lutea (CL) were less in ovulation-induced KO mice treated with estradiol compared to WT mice. Area of individual CL and serum concentrations of progesterone were greater in ovulation-induced KO mice given estradiol compared to WT mice. Ovulation-induced KO mice had more, larger hemorrhagic follicles than similarly treated WT mice, but hemorrhagic follicles were not influenced by estradiol. Proliferation of ovarian surface epithelial cells did not differ between KO and WT mice induced to ovulate and given estradiol. Ovaries from TP53 gene knockout mice (n = 4) induced to ovulate and given a 21-day estradiol implant three times over 58 days were observed for precursor lesions. There was no indication of precursor lesions in any TP53 KO or WT mouse. TP53 status did not influence recruitment of follicles, but TP53 deficiency hindered the ability of human chorionic gonadotropin to cause ovulation.
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Affiliation(s)
- Brenda M Alexander
- Department of Animal Science, University of Wyoming, Laramie, Wyoming 82071, USA.
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1198
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Abstract
In early studies on energy metabolism of tumor cells, it was proposed that the enhanced glycolysis was induced by a decreased oxidative phosphorylation. Since then it has been indiscriminately applied to all types of tumor cells that the ATP supply is mainly or only provided by glycolysis, without an appropriate experimental evaluation. In this review, the different genetic and biochemical mechanisms by which tumor cells achieve an enhanced glycolytic flux are analyzed. Furthermore, the proposed mechanisms that arguably lead to a decreased oxidative phosphorylation in tumor cells are discussed. As the O(2) concentration in hypoxic regions of tumors seems not to be limiting for the functioning of oxidative phosphorylation, this pathway is re-evaluated regarding oxidizable substrate utilization and its contribution to ATP supply versus glycolysis. In the tumor cell lines where the oxidative metabolism prevails over the glycolytic metabolism for ATP supply, the flux control distribution of both pathways is described. The effect of glycolytic and mitochondrial drugs on tumor energy metabolism and cellular proliferation is described and discussed. Similarly, the energy metabolic changes associated with inherent and acquired resistance to radiotherapy and chemotherapy of tumor cells, and those determined by positron emission tomography, are revised. It is proposed that energy metabolism may be an alternative therapeutic target for both hypoxic (glycolytic) and oxidative tumors.
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Affiliation(s)
- Rafael Moreno-Sánchez
- Instituto Nacional de Cardiología, Departamento de Bioquímica, Juan Badiano no. 1, Tlalpan, México DF 14080, Mexico.
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1199
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Cairns RA, Papandreou I, Sutphin PD, Denko NC. Metabolic targeting of hypoxia and HIF1 in solid tumors can enhance cytotoxic chemotherapy. Proc Natl Acad Sci U S A 2007; 104:9445-50. [PMID: 17517659 PMCID: PMC1890514 DOI: 10.1073/pnas.0611662104] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2006] [Indexed: 12/26/2022] Open
Abstract
Solid tumors frequently contain large regions with low oxygen concentrations (hypoxia). The hypoxic microenvironment induces adaptive changes to tumor cell metabolism, and this alteration can further distort the local microenvironment. The net result of these tumor-specific changes is a microenvironment that inhibits many standard cytotoxic anticancer therapies and predicts for a poor clinical outcome. Pharmacologic targeting of the unique metabolism of solid tumors could alter the tumor microenvironment to provide more favorable conditions for anti-tumor therapy. Here, we describe a strategy in which the mitochondrial metabolism of tumor cells is increased by pharmacologic inhibition of hypoxia-inducible factor 1 (HIF1) or its target gene pyruvate dehydrogenase kinase 1 (PDK1). This acute increase in oxygen consumption leads to a corresponding decrease in tumor oxygenation. Whereas decreased oxygenation could reduce the effectiveness of some traditional therapies, we show that it dramatically increases the effectiveness of a hypoxia-specific cytotoxin. This treatment strategy should provide a high degree of tumor specificity for increasing the effectiveness of hypoxic cytotoxins, as it depends on the activation of HIF1 and the presence of hypoxia, conditions that are present only in the tumor, and not the normal tissue.
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Affiliation(s)
- Rob A. Cairns
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305
| | - Ioanna Papandreou
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305
| | - Patrick D. Sutphin
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305
| | - Nicholas C. Denko
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305
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1200
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Chen ZX, Pervaiz S. Bcl-2 induces pro-oxidant state by engaging mitochondrial respiration in tumor cells. Cell Death Differ 2007; 14:1617-27. [PMID: 17510660 DOI: 10.1038/sj.cdd.4402165] [Citation(s) in RCA: 120] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Mitochondrial respiration, the key process behind cellular energy production, is critical for cell proliferation, growth and survival. However, the regulation of mitochondrial respiratory function in tumor cells is not well understood. In this study, we propose a model whereby tumor cells possess the capacity to fine-tune the balance between energy demands and mitochondrial reactive oxygen species (ROS) status, to maintain a milieu optimal for survival. This is achieved through the moderation of mitochondrial respiration, depending on the ROS context within the organelle, with the main players being Bcl-2 and cytochrome c oxidase (COX). We report a higher level of COX activity, oxygen consumption and mitochondrial respiration in tumor cells overexpressing Bcl-2. Transient overexpression, gene silencing and pharmacological inhibition of Bcl-2 corroborate these findings. Interestingly, Bcl-2 is also able to regulate mitochondrial respiration and COX activity in the face of mounting ROS levels, triggered by mitochondrial complex inhibitors. In this respect, it is plausible to suggest that Bcl-2 may be able to create an environment, most suited for survival by adjusting mitochondrial respiration accordingly to meet energy requirements, without incurring an overwhelming, detrimental increase in intracellular ROS.
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Affiliation(s)
- Z X Chen
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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