101
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Blake DM, Tomovic S, Jyung RW. Tympanic Paraganglioma. EAR, NOSE & THROAT JOURNAL 2014. [DOI: 10.1177/0145561314093004-503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Danielle M. Blake
- Department of Otolaryngology-Head and Neck Surgery,
Rutgers New Jersey Medical School, Newark, N.J
| | - Senja Tomovic
- Department of Otolaryngology-Head and Neck Surgery,
Rutgers New Jersey Medical School, Newark, N.J
| | - Robert W. Jyung
- Department of Otolaryngology-Head and Neck Surgery,
Rutgers New Jersey Medical School, Newark, N.J
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102
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Unsuspected task for an old team: succinate, fumarate and other Krebs cycle acids in metabolic remodeling. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:1330-7. [PMID: 24699309 DOI: 10.1016/j.bbabio.2014.03.013] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 03/17/2014] [Accepted: 03/25/2014] [Indexed: 12/15/2022]
Abstract
Seventy years from the formalization of the Krebs cycle as the central metabolic turntable sustaining the cell respiratory process, key functions of several of its intermediates, especially succinate and fumarate, have been recently uncovered. The presumably immutable organization of the cycle has been challenged by a number of observations, and the variable subcellular location of a number of its constitutive protein components is now well recognized, although yet unexplained. Nonetheless, the most striking observations have been made in the recent period while investigating human diseases, especially a set of specific cancers, revealing the crucial role of Krebs cycle intermediates as factors affecting genes methylation and thus cell remodeling. We review here the recent advances and persisting incognita about the role of Krebs cycle acids in diverse aspects of cellular life and human pathology.
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103
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Role of VEGF-A and its receptors in sporadic and MEN2-associated pheochromocytoma. Int J Mol Sci 2014; 15:5323-36. [PMID: 24675699 PMCID: PMC4013566 DOI: 10.3390/ijms15045323] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 03/18/2014] [Accepted: 03/18/2014] [Indexed: 01/28/2023] Open
Abstract
Pheochromocytoma (PHEO), a rare catecholamine producing tumor arising from the chromaffin cells, may occurs sporadically (76%–80%) or as part of inherited syndromes (20%–24%). Angiogenesis is a fundamental step in tumor proliferation and vascular endothelial growth factor (VEGF-A) is the most well-characterized angiogenic factor. The role of angiogenic markers in PHEO is not fully understood; investigations were therefore made to evaluate the expression of VEGF-A and its receptors in PHEO and correlate to clinical parameters. Twenty-nine samples of PHEO were evaluated for VEGF-A, VEGF receptor-1 (VEGFR-1) VEGFR-2 expression and microvessel density (MVD) by immunohistochemistry. Clinical data were reviewed in medical records. The mean age of patients was 38 ± 14 years, and 69% were woman. VEGF-A, VEGFR-1 and VEGFR-2 staining were detected in nearly all PHEO samples. No significant correlation was observed between VEGF-A, VEGFR-1, VEGFR-2 expression or MVD and age at diagnosis, tumor size or sporadic and hereditary PHEO. However, the levels of expression of these molecules were significantly higher in malignant PHEO samples (p = 0.027, p = 0.003 and p = 0.026, respectively).VEGF-A and its receptors were shown to be up-regulated in malignant PHEO, suggesting that these molecules might be considered as therapeutic targets for unresectable or metastatic tumors.
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104
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Wang X, Peralta S, Moraes CT. Mitochondrial alterations during carcinogenesis: a review of metabolic transformation and targets for anticancer treatments. Adv Cancer Res 2014; 119:127-60. [PMID: 23870511 DOI: 10.1016/b978-0-12-407190-2.00004-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Mitochondria play important roles in multiple cellular processes including energy metabolism, cell death, and aging. Regulated energy production and utilization are critical in maintaining energy homeostasis in normal cells and functional organs. However, mitochondria go through a series of morphological and functional alterations during carcinogenesis. The metabolic profile in transformed cells is altered to accommodate their fast proliferation, confer resistance to cell death, or facilitate metastasis. These transformations also provide targets for anticancer treatment at different levels. In this review, we discuss the major modifications in cell metabolism during carcinogenesis, including energy metabolism, apoptotic and autophagic cell death, adaptation of tumor microenvironment, and metastasis. We also summarize some of the main metabolic targets for treatments.
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Affiliation(s)
- Xiao Wang
- Graduate Program in Cancer Biology, Department of Neurology, University of Miami Miller School of Medicine, Miami, Florida, USA
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105
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Menendez JA, Alarcón T, Joven J. Gerometabolites: the pseudohypoxic aging side of cancer oncometabolites. Cell Cycle 2014; 13:699-709. [PMID: 24526120 DOI: 10.4161/cc.28079] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Oncometabolites are defined as small-molecule components (or enantiomers) of normal metabolism whose accumulation causes signaling dysregulation to establish a milieu that initiates carcinogenesis. In a similar manner, we propose the term "gerometabolites" to refer to small-molecule components of normal metabolism whose depletion causes signaling dysregulation to establish a milieu that drives aging. In an investigation of the pathogenic activities of the currently recognized oncometabolites R(-)-2-hydroxyglutarate (2-HG), fumarate, and succinate, which accumulate due to mutations in isocitrate dehydrogenases (IDH), fumarate hydratase (FH), and succinate dehydrogenase (SDH), respectively, we illustrate the fact that metabolic pseudohypoxia, the accumulation of hypoxia-inducible factor (HIFα) under normoxic conditions, and the subsequent Warburg-like reprogramming that shifts glucose metabolism from the oxidative pathway to aerobic glycolysis are the same mechanisms through which the decline of the "gerometabolite" nicotinamide adenine dinucleotide (NAD)(+) reversibly disrupts nuclear-mitochondrial communication and contributes to the decline in mitochondrial function with age. From an evolutionary perspective, it is reasonable to view NAD(+)-driven mitochondrial homeostasis as a conserved response to changes in energy supplies and oxygen levels. Similarly, the natural ability of 2-HG to significantly alter epigenetics might reflect an evolutionarily ancient role of certain metabolites to signal for elevated glutamine/glutamate metabolism and/or oxygen deficiency. However, when chronically altered, these responses become conserved causes of aging and cancer. Because HIFα-driven pseudohypoxia might drive the overproduction of 2-HG, the intriguing possibility exists that the decline of gerometabolites such as NAD(+) could promote the chronic accumulation of oncometabolites in normal cells during aging. If the sole activation of a Warburg-like metabolic reprogramming in normal tissues might be able to significantly increase the endogenous production of bona fide etiological determinants in cancer, such as oncometabolites, this undesirable trade-off between mitochondrial dysfunction and activation of oncometabolites production might then pave the way for the epigenetic initiation of carcinogenesis in a strictly metabolic-dependent manner. Perhaps it is time to definitely adopt the view that aging and aging diseases including cancer are governed by a pivotal regulatory role of metabolic reprogramming in cell fate decisions.
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Affiliation(s)
- Javier A Menendez
- Metabolism & Cancer Group; Translational Research Laboratory; Catalan Institute of Oncology; Girona, Spain; Molecular Oncology Group; Girona Biomedical Research Institute (IDIBGI); Girona, Spain
| | - Tomás Alarcón
- Computational & Mathematical Biology Research Group; Centre de Recerca Matemàtica (CRM); Barcelona, Spain
| | - Jorge Joven
- Unitat de Recerca Biomèdica (URB-CRB); Institut d'Investigació Sanitaria Pere i Virgili (IISPV); Universitat Rovira i Virgili; Reus, Spain
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106
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Hansel DE, Rini BI. Molecular genetics of hereditary renal cancer: new genes and diagnostic and therapeutic opportunities. Expert Rev Anticancer Ther 2014; 8:895-905. [DOI: 10.1586/14737140.8.6.895] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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107
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Prasad C, Oakley GJ, Yip L, Coyne C, Rangaswamy B, Dixit SB. A novel mutation in the succinate dehydrogenase subunit D gene in siblings with the hereditary paraganglioma-pheochromocytoma syndrome. SAGE Open Med Case Rep 2014; 2:2050313X14553520. [PMID: 27489656 PMCID: PMC4857366 DOI: 10.1177/2050313x14553520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 09/07/2014] [Indexed: 11/20/2022] Open
Abstract
Germline mutations in the succinate dehydrogenase complex subunit D gene are now known to be associated with hereditary paraganglioma–pheochromocytoma syndromes. Since the initial succinate dehydrogenase complex subunit D gene mutation was identified about a decade ago, more than 131 unique variants have been reported. We report the case of two siblings presenting with multiple paragangliomas and pheochromocytomas; they were both found to carry a mutation in the succinate dehydrogenase complex subunit D gene involving a substitution of thymine to guanine at nucleotide 236 in exon 3. This particular mutation of the succinate dehydrogenase complex subunit D gene has only been reported in one previous patient in Japan; this is, therefore, the first report of this pathogenic mutation in siblings and the first report of this mutation in North America. With continued screening of more individuals, we will be able to create a robust mutation database that can help us understand disease patterns associated with particular variants and may be a starting point in the development of new therapies for familial paraganglioma syndromes.
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Affiliation(s)
- Chaithra Prasad
- Division of Endocrinology, Diabetes, and Metabolism, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Gerard J Oakley
- Department of Pathology, Marshall University, Huntington, WV, USA
| | - Linwah Yip
- Division of Endocrine Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Christopher Coyne
- Division of Endocrinology, Diabetes, and Metabolism, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | | | - Sanjay B Dixit
- Division of Endocrinology, Diabetes, and Metabolism, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
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108
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Nutritional Approaches for Healthy Aging of the Brain and the Prevention of Neurodegenerative Diseases. PHARMA-NUTRITION 2014. [DOI: 10.1007/978-3-319-06151-1_23] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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109
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Marden JH. Nature's inordinate fondness for metabolic enzymes: why metabolic enzyme loci are so frequently targets of selection. Mol Ecol 2013; 22:5743-64. [PMID: 24106889 DOI: 10.1111/mec.12534] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Revised: 09/11/2013] [Accepted: 09/17/2013] [Indexed: 01/01/2023]
Abstract
Metabolic enzyme loci were some of the first genes accessible for molecular evolution and ecology research. New technologies now make the whole genome, transcriptome or proteome readily accessible, allowing unbiased scans for loci exhibiting significant differences in allele frequency or expression level and associated with phenotypes and/or responses to natural selection. With surprising frequency and in many cases in proportions greater than chance relative to other genes, glycolysis and TCA cycle enzyme loci appear among the genes with significant associations in these studies. Hence, there is an ongoing need to understand the basis for fitness effects of metabolic enzyme polymorphisms. Allele-specific effects on the binding affinity and catalytic rate of individual enzymes are well known, but often of uncertain significance because metabolic control theory and in vivo studies indicate that many individual metabolic enzymes do not affect pathway flux rate. I review research, so far little used in evolutionary biology, showing that metabolic enzyme substrates affect signalling pathways that regulate cell and organismal biology, and that these enzymes have moonlighting functions. To date there is little knowledge of how alleles in natural populations affect these phenotypes. I discuss an example in which alleles of a TCA enzyme locus associate with differences in a signalling pathway and development, organismal performance, and ecological dynamics. Ultimately, understanding how metabolic enzyme polymorphisms map to phenotypes and fitness remains a compelling and ongoing need for gaining robust knowledge of ecological and evolutionary processes.
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Affiliation(s)
- James H Marden
- Department of Biology, Pennsylvania State University, University Park, PA, 16802, USA
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110
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Yang M, Soga T, Pollard PJ. Oncometabolites: linking altered metabolism with cancer. J Clin Invest 2013; 123:3652-8. [PMID: 23999438 DOI: 10.1172/jci67228] [Citation(s) in RCA: 308] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The discovery of cancer-associated mutations in genes encoding key metabolic enzymes has provided a direct link between altered metabolism and cancer. Advances in mass spectrometry and nuclear magnetic resonance technologies have facilitated high-resolution metabolite profiling of cells and tumors and identified the accumulation of metabolites associated with specific gene defects. Here we review the potential roles of such "oncometabolites" in tumor evolution and as clinical biomarkers for the detection of cancers characterized by metabolic dysregulation.
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Affiliation(s)
- Ming Yang
- Cancer Biology and Metabolism Group, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
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111
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Thibault C, Gimenez-Roqueplo AP. Mutations de gènes impliqués dans le métabolisme énergétique et cancer. ONCOLOGIE 2013. [DOI: 10.1007/s10269-013-2320-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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112
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Jochmanová I, Yang C, Zhuang Z, Pacak K. Hypoxia-inducible factor signaling in pheochromocytoma: turning the rudder in the right direction. J Natl Cancer Inst 2013; 105:1270-83. [PMID: 23940289 DOI: 10.1093/jnci/djt201] [Citation(s) in RCA: 124] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Many solid tumors, including pheochromocytoma (PHEO) and paraganglioma (PGL), are characterized by a (pseudo)hypoxic signature. (Pseudo)hypoxia has been shown to promote both tumor progression and resistance to therapy. The major mediators of the transcriptional hypoxic response are hypoxia-inducible factors (HIFs). High levels of HIFs lead to transcription of hypoxia-responsive genes, which are involved in tumorigenesis. PHEOs and PGLs are catecholamine-producing tumors arising from sympathetic- or parasympathetic-derived chromaffin tissue. In recent years, substantial progress has been made in understanding the metabolic disturbances present in PHEO and PGL, especially because of the identification of some disease-susceptibility genes. To date, fifteen PHEO and PGL susceptibility genes have been identified. Based on the main transcription signatures of the mutated genes, PHEOs and PGLs have been divided into two clusters, pseudohypoxic cluster 1 and cluster 2, rich in kinase receptor signaling and protein translation pathways. Although these two clusters seem to show distinct signaling pathways, recent data suggest that both clusters are interconnected by HIF signaling as the important driver in their tumorigenesis, and mutations in most PHEO and PGL susceptibility genes seem to affect HIF-α regulation and its downstream signaling pathways. HIF signaling appears to play an important role in the development and growth of PHEOs and PGLs, which could suggest new therapeutic approaches for the treatment of these tumors.
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Affiliation(s)
- Ivana Jochmanová
- Program in Reproductive and Adult Endocrinology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-1109, USA
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113
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Naranjo-Suarez S, Carlson BA, Tobe R, Yoo MH, Tsuji PA, Gladyshev VN, Hatfield DL. Regulation of HIF-1α activity by overexpression of thioredoxin is independent of thioredoxin reductase status. Mol Cells 2013; 36:151-7. [PMID: 23912593 PMCID: PMC3887957 DOI: 10.1007/s10059-013-0121-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 06/15/2013] [Accepted: 06/17/2013] [Indexed: 10/26/2022] Open
Abstract
Under hypoxic conditions, cells activate a transcriptional response mainly driven by hypoxia-inducible factors (HIFs). HIF-1α stabilization and activity are known to be regulated by thioredoxin 1 (Txn1), but how the thioredoxin system regulates the hypoxic response is unknown. By examining the effects of Txn1 overexpression on HIF-1α function in HeLa, HT-29, MCF-7 and EMT6 cell lines, we found that this oxidoreductase did not stabilize HIF-1α, yet could increase its activity. These effects were dependent on the redox function of Txn1. However, Txn1 deficiency did not affect HIF-1α hypoxic-stabilization and activity, and overexpression of thioredoxin reductase 1 (TR1), the natural Txn1 reductase, had no influence on HIF-1α activity. Moreover, overexpression of Txn1 in TR1 deficient HeLa and EMT6 cells was still able to increase HIF-1α hypoxic activity. These results indicate that Txn1 is not essential for HIF-1α hypoxic stabilization or activity, that its overexpression can increase HIF-1α hypoxic activity, and that this effect is observed regardless of TR1 status. Thus, regulation of HIF-1α by the thioredoxin system depends on the specific levels of this system's major components.
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Affiliation(s)
- Salvador Naranjo-Suarez
- Molecular Biology of Selenium Section, Laboratory of Cancer Prevention, Center for Cancer Research, National Institutes of Health, Bethesda, MD 20892,
USA
- Present address: Department of Pathology, The Sol Goldman Pancreatic Cancer Research Center, John Hopkins Medical Institution, Baltimore, MD 21231,
USA
| | - Bradley A. Carlson
- Molecular Biology of Selenium Section, Laboratory of Cancer Prevention, Center for Cancer Research, National Institutes of Health, Bethesda, MD 20892,
USA
| | - Ryuta Tobe
- Molecular Biology of Selenium Section, Laboratory of Cancer Prevention, Center for Cancer Research, National Institutes of Health, Bethesda, MD 20892,
USA
| | - Min-Hyuk Yoo
- Molecular Biology of Selenium Section, Laboratory of Cancer Prevention, Center for Cancer Research, National Institutes of Health, Bethesda, MD 20892,
USA
| | - Petra A. Tsuji
- Department of Biological Sciences, Towson University, Towson, MD 21252,
USA
| | - Vadim N. Gladyshev
- Division of Genetics, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston MA, 02115,
USA
| | - Dolph L. Hatfield
- Molecular Biology of Selenium Section, Laboratory of Cancer Prevention, Center for Cancer Research, National Institutes of Health, Bethesda, MD 20892,
USA
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114
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Jimenez C, Rohren E, Habra MA, Rich T, Jimenez P, Ayala-Ramirez M, Baudin E. Current and future treatments for malignant pheochromocytoma and sympathetic paraganglioma. Curr Oncol Rep 2013; 15:356-71. [PMID: 23674235 DOI: 10.1007/s11912-013-0320-x] [Citation(s) in RCA: 116] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Pheochromocytomas (PHs) and sympathetic paragangliomas (SPGs) are rare neuroendocrine tumors. Approximately 17 % of these tumors are malignant, but because no molecular or histologic markers for malignancy exist, patients are often diagnosed with malignant PHs or SPGs after unresectable disease has formed. Patients with progressive metastatic tumors and overwhelming symptoms are currently treated with systemic chemotherapy and radiopharmaceutical agents such as metaiodobenzylguanidine. These therapies lead to partial radiographic response, disease stabilization, and symptomatic improvement in approximately 40 % of patients, and systemic chemotherapy is associated with a modest improvement in overall survival duration. However, over the past decade, substantial progress has been made in clinical, biochemical, and radiographic diagnosis of PHs and SPGs. Approximately 50 % of patients with malignant PHs and SPGs have been found to carry hereditary germline mutations in the succinate dehydrogenase subunit B gene (SDHB), and anti-angiogenic agents such as sunitinib have been found to potentially play a role in the treatment of malignant disease, especially in patients with SDHB mutations. In some patients, treatment with sunitinib has been associated with partial radiographic response, disease stabilization, decreased fluorodeoxyglucose uptake on positron emission tomography, and improved blood pressure control. These findings have led to the development of prospective clinical trials of new targeted therapies for metastatic disease. Here, we provide an updated review of the clinical and genetic predictors of malignant disease, radiographic diagnosis of malignant disease, and information from the most relevant studies of systemic therapies, as well as proposed treatment guidelines for patients with metastatic or potentially malignant PHs and SPGs.
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Affiliation(s)
- Camilo Jimenez
- Department of Endocrine Neoplasia and Hormonal Disorders, Unit 1461, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX 77030, USA.
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115
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Rao J, Engelke U, Rodenburg R, Wevers R, Pacak K, Eisenhofer G, Qin N, Kusters B, Goudswaard A, Lenders J, Hermus A, Mensenkamp A, Kunst H, Sweep F, Timmers H. Genotype-specific abnormalities in mitochondrial function associate with distinct profiles of energy metabolism and catecholamine content in pheochromocytoma and paraganglioma. Clin Cancer Res 2013; 19:3787-95. [PMID: 23723300 PMCID: PMC3715587 DOI: 10.1158/1078-0432.ccr-12-3922] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
PURPOSE Pheochromocytomas and paragangliomas (PGL) are neuroendocrine tumors of sympathetic and parasympathetic paraganglia. This study investigated the relationships between genotype-specific differences in mitochondrial function and catecholamine content in PGL tumors. EXPERIMENTAL DESIGN Respiratory chain enzyme assays and (1)H-nuclear magnetic resonance (NMR) spectroscopy at 500 MHz were conducted on homogenates of 35 sporadic PGLs and 59 PGLs from patients with hereditary mutations in succinate dehydrogenase subunits B and D (SDHB, SDHD), succinate dehydrogenase assembly factor 2, von Hippel-Lindau (VHL), rearranged during transfection (RET), neurofibromatosis type 1 (NF1), and myc-associated factor X. RESULTS In SDHx-related PGLs, a significant decrease in complex II activity (P < 0.0001) and a significant increase in complex I, III, and IV enzyme activities were observed when compared to sporadic, RET, and NF1 tumors. Also, a significant increase in citrate synthase (P < 0.0001) enzyme activity was observed in SDHx-related PGLs when compared to sporadic-, VHL-, RET-, and NF1-related tumors. An increase in succinate accumulation (P < 0.001) and decrease in ATP/ADP/AMP accumulation (P < 0.001) was observed when compared to sporadic PGLs and PGLs of other genotypes. Positive correlations (P < 0.01) were observed between respiratory chain complex II activity and total catecholamine content and ATP/ADP/AMP and total catecholamine contents in tumor tissues. CONCLUSIONS This study for the first time establishes a relationship between determinants of energy metabolism, like activity of respiratory chain enzyme complex II, ATP/ADP/AMP content, and catecholamine content in PGL tumors. Also, this study for the first time successfully uses NMR spectroscopy to detect catecholamines in PGL tumors and provides ex vivo evidence for the accumulation of succinate in PGL tumors with an SDHx mutation.
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Affiliation(s)
- J.U. Rao
- Department of Laboratory Medicine, Laboratory of Genetic Endocrine and Metabolic Diseases, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
- Department of Medicine, Division of Endocrinology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - U.F.H. Engelke
- Department of Laboratory Medicine, Laboratory of Genetic Endocrine and Metabolic Diseases, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - R.J.T. Rodenburg
- Department of Laboratory Medicine, Laboratory of Genetic Endocrine and Metabolic Diseases, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
- Department of Pediatrics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - R.A. Wevers
- Department of Laboratory Medicine, Laboratory of Genetic Endocrine and Metabolic Diseases, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - K. Pacak
- Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institute of Health, Bethesda, MD, USA
| | - G. Eisenhofer
- Department of Medicine and Institute of Clinical Chemistry & Laboratory Medicine, University Hospital Carl Gustav Carus, Dresden, Germany
| | - N. Qin
- Department of Medicine and Institute of Clinical Chemistry & Laboratory Medicine, University Hospital Carl Gustav Carus, Dresden, Germany
| | - B. Kusters
- Department of Pathology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
- Department of Pathology, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - A.G. Goudswaard
- Department of Laboratory Medicine, Laboratory of Genetic Endocrine and Metabolic Diseases, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - J.W.M Lenders
- Department of Medicine and Institute of Clinical Chemistry & Laboratory Medicine, University Hospital Carl Gustav Carus, Dresden, Germany
- Department of General Internal Medicine, division of Vascular Medicine, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - A.R.M.M. Hermus
- Department of Medicine, Division of Endocrinology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - A.R. Mensenkamp
- Department of Genetics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - H.P.M. Kunst
- Department of Otolaryngology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - F.C.G.J. Sweep
- Department of Laboratory Medicine, Laboratory of Genetic Endocrine and Metabolic Diseases, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - H.J.L.M. Timmers
- Department of Medicine, Division of Endocrinology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
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116
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Rare insights into cancer biology. Oncogene 2013; 33:2547-56. [PMID: 23812428 DOI: 10.1038/onc.2013.222] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Revised: 04/12/2013] [Accepted: 04/12/2013] [Indexed: 12/12/2022]
Abstract
Cancer-associated mutations have been identified in the metabolic genes succinate dehydrogenase (SDH), fumarate hydratase (FH) and isocitrate dehydrogenase (IDH), advancing and challenging our understanding of cellular function and disease mechanisms and providing direct links between dysregulated metabolism and cancer. Some striking parallels exist in the cellular consequences of the genetic mutations within this triad of cancer syndromes, including accumulation of oncometabolites and competitive inhibition of 2-oxoglutarate-dependent dioxygenases, particularly, hypoxia-inducible factor (HIF) prolyl hydroxylases, JmjC domain-containing histone demethylases (part of the JMJD family) and the ten-eleven translocation (TET) family of 5methyl cytosine (5mC) DNA hydroxylases. These lead to activation of HIF-dependent oncogenic pathways and inhibition of histone and DNA demethylation. Mutations in FH, resulting in loss of enzyme activity, predispose affected individuals to a rare cancer, hereditary leiomyomatosis and renal cell cancer (HLRCC), characterised by benign smooth muscle cutaneous and uterine tumours (leiomyomata) and an aggressive form of collecting duct and type 2 papillary renal cancer. Interestingly, loss of FH activity results in the accumulation of high levels of fumarate that can lead to the non-enzymatic modification of cysteine residues in multiple proteins (succination) and in some cases to their disrupted function. Here we consider that the study of rare diseases such as HLRCC, combining analyses of human tumours and cell lines with in vitro and in vivo murine models has provided novel insights into cancer biology associated with dysregulated metabolism and represents a useful paradigm for cancer research.
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117
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Hagl S, Kocher A, Schiborr C, Eckert SH, Ciobanu I, Birringer M, El-Askary H, Helal A, Khayyal MT, Frank J, Muller WE, Eckert GP. Rice bran extract protects from mitochondrial dysfunction in guinea pig brains. Pharmacol Res 2013; 76:17-27. [PMID: 23827162 DOI: 10.1016/j.phrs.2013.06.008] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Revised: 06/13/2013] [Accepted: 06/18/2013] [Indexed: 01/08/2023]
Abstract
Mitochondrial dysfunction plays a major role in the development of age-related neurodegenerative diseases and recent evidence suggests that food ingredients can improve mitochondrial function. In the current study we investigated the effects of feeding a stabilized rice bran extract (RBE) on mitochondrial function in the brain of guinea pigs. Key components of the rice bran are oryzanols, tocopherols and tocotrienols, which are supposed to have beneficial effects on mitochondrial function. Concentrations of α-tocotrienol and γ-carboxyethyl hydroxychroman (CEHC) but not γ-tocotrienol were significantly elevated in brains of RBE fed animals and thus may have provided protective properties. Overall respiration and mitochondrial coupling were significantly enhanced in isolated mitochondria, which suggests improved mitochondrial function in brains of RBE fed animals. Cells isolated from brains of RBE fed animals showed significantly higher mitochondrial membrane potential and ATP levels after sodium nitroprusside (SNP) challenge indicating resistance against mitochondrial dysfunction. Experimental evidence indicated increased mitochondrial mass in guinea pig brains, e.g. enhanced citrate synthase activity, increased cardiolipin as well as respiratory chain complex I and II and TIMM levels. In addition levels of Drp1 and fis1 were also increased in brains of guinea pigs fed RBE, indicating enhanced fission events. Thus, RBE represents a potential nutraceutical for the prevention of mitochondrial dysfunction and oxidative stress in brain aging and neurodegenerative diseases.
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118
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Letouzé E, Martinelli C, Loriot C, Burnichon N, Abermil N, Ottolenghi C, Janin M, Menara M, Nguyen AT, Benit P, Buffet A, Marcaillou C, Bertherat J, Amar L, Rustin P, De Reyniès A, Gimenez-Roqueplo AP, Favier J. SDH mutations establish a hypermethylator phenotype in paraganglioma. Cancer Cell 2013; 23:739-52. [PMID: 23707781 DOI: 10.1016/j.ccr.2013.04.018] [Citation(s) in RCA: 537] [Impact Index Per Article: 48.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2012] [Revised: 01/29/2013] [Accepted: 04/20/2013] [Indexed: 02/07/2023]
Abstract
Paragangliomas are neuroendocrine tumors frequently associated with mutations in RET, NF1, VHL, and succinate dehydrogenase (SDHx) genes. Methylome analysis of a large paraganglioma cohort identified three stable clusters, associated with distinct clinical features and mutational status. SDHx-related tumors displayed a hypermethylator phenotype, associated with downregulation of key genes involved in neuroendocrine differentiation. Succinate accumulation in SDH-deficient mouse chromaffin cells led to DNA hypermethylation by inhibition of 2-OG-dependent histone and DNA demethylases and established a migratory phenotype reversed by decitabine treatment. Epigenetic silencing was particularly severe in SDHB-mutated tumors, potentially explaining their malignancy. Finally, inactivating FH mutations were identified in the only hypermethylated tumor without SDHx mutations. These findings emphasize the interplay between the Krebs cycle, epigenomic changes, and cancer.
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Affiliation(s)
- Eric Letouzé
- Programme Cartes d'Identité des Tumeurs, Ligue Nationale Contre Le Cancer, 75013 Paris, France
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119
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Toledo RA, Qin Y, Srikantan S, Morales NP, Li Q, Deng Y, Kim SW, Pereira MAA, Toledo SP, Su X, Aguiar RCT, Dahia PLM. In vivo and in vitro oncogenic effects of HIF2A mutations in pheochromocytomas and paragangliomas. Endocr Relat Cancer 2013; 20:349-59. [PMID: 23533246 PMCID: PMC5944295 DOI: 10.1530/erc-13-0101] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Pheochromocytomas and paragangliomas are highly vascular tumors of the autonomic nervous system. Germline mutations, including those in hypoxia-related genes, occur in one third of the cases, but somatic mutations are infrequent in these tumors. Using exome sequencing of six paired constitutive and tumor DNA from sporadic pheochromocytomas and paragangliomas, we identified a somatic mutation in the HIF2A (EPAS1) gene. Screening of an additional 239 pheochromocytomas/paragangliomas uncovered three other HIF2A variants in sporadic (4/167, 2.3%) but not in hereditary tumors or controls. Three of the mutations involved proline 531, one of the two residues that controls HIF2α stability by hydroxylation. The fourth mutation, on Ser71, was adjacent to the DNA binding domain. No mutations were detected in the homologous regions of the HIF1A gene in 132 tumors. Mutant HIF2A tumors had increased expression of HIF2α target genes, suggesting an activating effect of the mutations. Ectopically expressed HIF2α mutants in HEK293, renal cell carcinoma 786-0, or rat pheochromocytoma PC12 cell lines showed increased stability, resistance to VHL-mediated degradation, target induction, and reduced chromaffin cell differentiation. Furthermore, mice injected with cells expressing mutant HIF2A developed tumors, and those with Pro531Thr and Pro531Ser mutations had shorter latency than tumors from mice with wild-type HIF2A. Our results support a direct oncogenic role for HIF2A in human neoplasia and strengthen the link between hypoxic pathways and pheochromocytomas and paragangliomas.
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Affiliation(s)
- Rodrigo A. Toledo
- Division of Hematology and Medical Oncology, Dept. Medicine, Cancer Therapy and Research Center at the University of Texas Health Science Center, San Antonio, Texas
| | - Yuejuan Qin
- Division of Hematology and Medical Oncology, Dept. Medicine, Cancer Therapy and Research Center at the University of Texas Health Science Center, San Antonio, Texas
| | - Subramanya Srikantan
- Division of Hematology and Medical Oncology, Dept. Medicine, Cancer Therapy and Research Center at the University of Texas Health Science Center, San Antonio, Texas
| | - Nicole Paes Morales
- Division of Hematology and Medical Oncology, Dept. Medicine, Cancer Therapy and Research Center at the University of Texas Health Science Center, San Antonio, Texas
| | - Qun Li
- Division of Hematology and Medical Oncology, Dept. Medicine, Cancer Therapy and Research Center at the University of Texas Health Science Center, San Antonio, Texas
| | - Yilun Deng
- Division of Hematology and Medical Oncology, Dept. Medicine, Cancer Therapy and Research Center at the University of Texas Health Science Center, San Antonio, Texas
| | - Sang-Woo Kim
- Division of Hematology and Medical Oncology, Dept. Medicine, Cancer Therapy and Research Center at the University of Texas Health Science Center, San Antonio, Texas
| | | | | | | | - Ricardo C. T. Aguiar
- Division of Hematology and Medical Oncology, Dept. Medicine, Cancer Therapy and Research Center at the University of Texas Health Science Center, San Antonio, Texas
- Greehey Children Cancer Research Institute, San Antonio, Texas
| | - Patricia L. M. Dahia
- Division of Hematology and Medical Oncology, Dept. Medicine, Cancer Therapy and Research Center at the University of Texas Health Science Center, San Antonio, Texas
- Greehey Children Cancer Research Institute, San Antonio, Texas
- corresponding author: Patricia Dahia, MD, PhD, Dept. Medicine, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, MC 7880, San Antonio-TX 78229-3900, Tel: (210) 567-4866, Fax: (210) 567-1956,
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120
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Zhang D, Wang W, Xiang B, Li N, Huang S, Zhou W, Sun Y, Wang X, Ma J, Li G, Li X, Shen S. Reduced succinate dehydrogenase B expression is associated with growth and de-differentiation of colorectal cancer cells. Tumour Biol 2013; 34:2337-47. [PMID: 23645213 DOI: 10.1007/s13277-013-0781-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Accepted: 03/26/2013] [Indexed: 01/07/2023] Open
Abstract
Succinate dehydrogenases (SDH), including SDHA, SDHB, SDHC, and SDHD, form the respiratory complex II in the mitochondria and play an important role in cell growth and homeostasis. In order to evaluate the expression and functional significance of SDH in colorectal cancer, the expression of four SDH subunits was analyzed, and SDHB protein was found to be significantly lower in colorectal cancer tissues. In vitro experiments including cell growth assay, colony formation assay, cell cycle analysis, and nude mouse xenograft of SDHB-transfected colorectal cancer cell line SW620 were performed. Notably, reduced SDHB expression in tumor tissues was associated with tumor de-differentiation, and restoration of SDHB could inhibit the growth of cancer cells both in vitro and in vivo. Furthermore, cDNA microarray of SDHB-transfected cell line showed that most of the differentially expressed genes are related to cell cycle control and cell proliferation. Thus, we conclude that SDHB expression is significantly decreased in human colorectal cancer tissues, and reconstitution of SDHB in colorectal cancer may be a potential therapeutic approach to inhibit aggressiveness of colorectal cancer.
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Affiliation(s)
- Decai Zhang
- Department of Gastroenterology, The Third Xiangya Hospital of Central South University, Changsha, 410013, Hunan, China
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121
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Grimm S. Respiratory chain complex II as general sensor for apoptosis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1827:565-72. [DOI: 10.1016/j.bbabio.2012.09.009] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 09/09/2012] [Accepted: 09/10/2012] [Indexed: 01/05/2023]
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122
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Abstract
Neuroendocrine tumors (NETs) present a wide spectrum of malignant diseases from rather benign to very malignant variants. The majority of these tumors are sporadic, but there are several familial (inherited) syndromes to consider, such as multiple endocrine neoplasia type 1 and type 2 (MEN-1 and MEN-2), von Hippel-Lindau syndrome (VHL), tuberosclerosis, and neurofibromatosis syndromes. The MEN-1 gene is mutated not only in MEN-1 families, but a recent study shows that more than 40% of sporadic pancreatic NETs (PNETs) harbor MEN-1 gene mutations. The same study reported that ATRX/DAXX genes are mutated in a significant number of tumors, as are genes encoding components of the mammalian target of rapamycin (mTOR) signal transduction pathway. These findings have implications for the new therapies that have been approved for the treatment of PNETs, such as the tyrosine kinase inhibitor sunitinib, as well the mTOR inhibitor everolimus. Small intestinal NETs show a less varied mutational pattern in that the majority of genetic alterations are found on chromosome 18. There seem to be no differences between the sporadic and the familiar type of small intestinal NETs (carcinoids). A wide range of genetic alterations have been described for the different subtypes of NETs, but the mechanisms underlying tumor development are essentially unknown except for MEN-2, in which an activating mutation of the RET proto-oncogene drives tumor progression and affords a direct genotype/phenotype correlation. Genome-wide screening of different types of NETs can now be performed for a reasonable price and is likely to generate new insights into the tumor biology and carcinogenesis in various subtypes of NETs.
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Affiliation(s)
- Kjell Öberg
- Department of Endocrine Oncology, Uppsala University Hospital, Uppsala, Sweden.
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123
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Tannahill GM, Curtis AM, Adamik J, Palsson-McDermott EM, McGettrick AF, Goel G, Frezza C, Bernard NJ, Kelly B, Foley NH, Zheng L, Gardet A, Tong Z, Jany SS, Corr SC, Haneklaus M, Caffrey BE, Pierce K, Walmsley S, Beasley FC, Cummins E, Nizet V, Whyte M, Taylor CT, Lin H, Masters SL, Gottlieb E, Kelly VP, Clish C, Auron PE, Xavier RJ, O'Neill LAJ. Succinate is an inflammatory signal that induces IL-1β through HIF-1α. Nature 2013; 496:238-42. [PMID: 23535595 PMCID: PMC4031686 DOI: 10.1038/nature11986] [Citation(s) in RCA: 2672] [Impact Index Per Article: 242.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Accepted: 02/05/2013] [Indexed: 01/27/2023]
Abstract
Macrophages activated by the Gram-negative bacterial product lipopolysaccharide switch their core metabolism from oxidative phosphorylation to glycolysis. Here we show that inhibition of glycolysis with 2-deoxyglucose suppresses lipopolysaccharide-induced interleukin-1β but not tumour-necrosis factor-α in mouse macrophages. A comprehensive metabolic map of lipopolysaccharide-activated macrophages shows upregulation of glycolytic and downregulation of mitochondrial genes, which correlates directly with the expression profiles of altered metabolites. Lipopolysaccharide strongly increases the levels of the tricarboxylic-acid cycle intermediate succinate. Glutamine-dependent anerplerosis is the principal source of succinate, although the 'GABA (γ-aminobutyric acid) shunt' pathway also has a role. Lipopolysaccharide-induced succinate stabilizes hypoxia-inducible factor-1α, an effect that is inhibited by 2-deoxyglucose, with interleukin-1β as an important target. Lipopolysaccharide also increases succinylation of several proteins. We therefore identify succinate as a metabolite in innate immune signalling, which enhances interleukin-1β production during inflammation.
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Affiliation(s)
- G M Tannahill
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland
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124
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Wojtovich AP, Smith CO, Haynes CM, Nehrke KW, Brookes PS. Physiological consequences of complex II inhibition for aging, disease, and the mKATP channel. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1827:598-611. [PMID: 23291191 DOI: 10.1016/j.bbabio.2012.12.007] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Revised: 12/14/2012] [Accepted: 12/17/2012] [Indexed: 12/21/2022]
Abstract
In recent years, it has become apparent that there exist several roles for respiratory complex II beyond metabolism. These include: (i) succinate signaling, (ii) reactive oxygen species (ROS) generation, (iii) ischemic preconditioning, (iv) various disease states and aging, and (v) a role in the function of the mitochondrial ATP-sensitive K(+) (mKATP) channel. This review will address the involvement of complex II in each of these areas, with a focus on how complex II regulates or may be involved in the assembly of the mKATP. This article is part of a Special Issue entitled: Respiratory complex II: Role in cellular physiology and disease.
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Affiliation(s)
- Andrew P Wojtovich
- Department of Medicine, University of Rochester Medical Center, Rochester, NY, USA
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125
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Marden JH, Fescemyer HW, Schilder RJ, Doerfler WR, Vera JC, Wheat CW. GENETIC VARIATION IN HIF SIGNALING UNDERLIES QUANTITATIVE VARIATION IN PHYSIOLOGICAL AND LIFE-HISTORY TRAITS WITHIN LOWLAND BUTTERFLY POPULATIONS. Evolution 2012; 67:1105-15. [DOI: 10.1111/evo.12004] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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126
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Hoekstra AS, Bayley JP. The role of complex II in disease. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1827:543-51. [PMID: 23174333 DOI: 10.1016/j.bbabio.2012.11.005] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Revised: 11/06/2012] [Accepted: 11/09/2012] [Indexed: 01/11/2023]
Abstract
Genetically defined mitochondrial deficiencies that result in the loss of complex II function lead to a range of clinical conditions. An array of tumor syndromes caused by complex II-associated gene mutations, in both succinate dehydrogenase and associated accessory factor genes (SDHA, SDHB, SDHC, SDHD, SDHAF1, SDHAF2), have been identified over the last 12 years and include hereditary paraganglioma-pheochromocytomas, a diverse group of renal cell carcinomas, and a specific subtype of gastrointestinal stromal tumors (GIST). In addition, congenital complex II deficiencies due to inherited homozygous mutations of the catalytic components of complex II (SDHA and SDHB) and the SDHAF1 assembly factor lead to childhood disease including Leigh syndrome, cardiomyopathy and infantile leukodystrophies. The role of complex II subunit gene mutations in tumorigenesis has been the subject of intensive research and these data have led to a variety of compelling hypotheses. Among the most widely researched are the stabilization of hypoxia inducible factor 1 under normoxia, and the generation of reactive oxygen species due to defective succinate:ubiquinone oxidoreductase function. Further progress in understanding the role of complex II in disease, and in the development of new therapeutic approaches, is now being hampered by the lack of relevant cell and animal models. This article is part of a Special Issue entitled: Respiratory complex II: Role in cellular physiology and disease.
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Affiliation(s)
- Attje S Hoekstra
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
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127
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Model animals for the study of oxidative stress from complex II. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1827:588-97. [PMID: 23142169 DOI: 10.1016/j.bbabio.2012.10.016] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Revised: 10/25/2012] [Accepted: 10/27/2012] [Indexed: 01/01/2023]
Abstract
Mitochondria play a role of energy production and produce intracellular reactive oxygen species (ROS), especially superoxide anion (O2(-)) as a byproduct of energy metabolism at the same time. O2(-) is converted from oxygen and is overproduced by excessive electron leakage from the mitochondrial respiratory chain. It is well known that mitochondrial complexes I and III in the electron transport system are the major endogenous ROS sources. We have previously demonstrated that mutations in complex II can result in excessive ROS (specifically in SDHC: G71E in Caenorhabditis elegans, I71E in Drosophila and V69E in mouse). Moreover, this results in premature death in C. elegans and Drosophila as well as tumorigenesis in mouse embryonic fibroblast cells. In humans, it has been reported that mutations in SDHB, SDHC or SDHD, which are the subunits of mitochondrial complex II, often result in inherited head and neck paragangliomas (PGLs). Recently, we established Tet-mev-1 conditional transgenic mice using our uniquely developed Tet-On/Off system, which can induce the mutated SDHC gene to be equally and competitively expressed compared to the endogenous wild-type SDHC gene. These mice experienced mitochondrial respiratory chain dysfunction that resulted in oxidative stress. The mitochondrial oxidative stress caused excessive apoptosis in several tissues leading to low-birth-weight infants and growth retardation during neonatal developmental phase in Tet-mev-1 mice. Tet-mev-1 mice also displayed precocious age-dependent corneal physiological changes, delayed corneal epithelialization, decreased corneal endothelial cells, thickened Descemet's membrane and thinning of parenchyma with corneal pathological dysfunctions such as keratitis, Fuchs' corneal dystrophy (FCD) and probably keratoconus after the normal development and growth phase. Here, we review the relationships between mitochondrial oxidative stress and phenomena in mev-1 animal models with mitochondrial complex II SDHC mutations. This article is part of a Special Issue entitled: Respiratory complex II: Role in cellular physiology and disease.
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128
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Aita Y, Ishii KA, Saito Y, Ikeda T, Kawakami Y, Shimano H, Hara H, Takekoshi K. Sunitinib inhibits catecholamine synthesis and secretion in pheochromocytoma tumor cells by blocking VEGF receptor 2 via PLC-γ-related pathways. Am J Physiol Endocrinol Metab 2012; 303:E1006-14. [PMID: 22912364 DOI: 10.1152/ajpendo.00156.2012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Sunitinib is an oral, small molecule multitargeted receptor tyrosine kinase inhibitor with antiangiogenic and antitumor activity that primarily targets vascular endothelial growth factor receptors (VEGFRs). Although sunitinib is an active agent for the treatment of malignant pheochromocytomas, it is unclear whether sunitinib acts through only antiangiogenic mechanisms or also directly targets tumor cells. We previously showed that sunitinib directly induced apoptosis of PC-12 cells. To further confirm these direct effects, we examined the effects of sunitinib on tyrosine hydroxylase (TH) (the rate-limiting enzyme in catecholamine biosynthesis) activity and catecholamine secretion in PC-12 cells and the underlying mechanisms. Sunitinib inhibited TH activity in a dose-dependent manner, and decreased TH protein levels. Consistent with this finding, sunitinib decreased TH phosphorylation at Ser(31) and Ser(40) and significantly decreased catecholamine secretion. VEGFR-2 knockdown attenuated these effects, including inhibition of TH activity and catecholamine secretion, suggesting that they were mediated by VEGFR-2. Sunitinib significantly decreased phospholipase C (PLC)-γ phosphorylation and subsequent protein kinase C (PKC) activity. Because Ser(40) phosphorylation significantly affects TH activity and is known to be regulated by PKC, sunitinib may inhibit Ser(40) phosphorylation via the VEGFR-2/PLC-γ/PKC pathway. Additionally, sunitinib markedly decreased the activity of extracellular signal-regulated kinase (ERK), but not c-Jun NH(2)-terminal kinase or p38 mitogen-activated protein kinase. Therefore, sunitinib may reduce TH Ser(31) phosphorylation through inhibition of the VEGFR-2/PLC-γ/PKC/Raf/mitogen-activated protein kinase/extracellular signal-regulated kinase kinase/ERK pathway. Sunitinib also significantly reduced inositol 1,4,5-trisphosphate production. However, because PC-12 cells do not precisely reflect the pathogenesis of malignant cells, we confirmed the key findings in a human neuroblastoma cell line, SK-N-SH. In conclusion, sunitinib directly inhibits catecholamine synthesis and secretion in pheochromocytoma PC-12 cells.
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Affiliation(s)
- Yuichi Aita
- Department of Molecular Laboratory Medicine, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
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129
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Succinate dehydrogenase B subunit immunohistochemical expression predicts aggressiveness in well differentiated neuroendocrine tumors of the ileum. Cancers (Basel) 2012; 4:808-20. [PMID: 24213468 PMCID: PMC3712706 DOI: 10.3390/cancers4030808] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 08/06/2012] [Accepted: 08/09/2012] [Indexed: 12/22/2022] Open
Abstract
Immunohistochemical loss of the succinate dehydrogenase subunit B (SDHB) has recently been reported as a surrogate biomarker of malignancy in sporadic and familial pheocromocytomas and paragangliomas through the activation of hypoxia pathways. However, data on the prevalence and the clinical implications of SDHB immunoreactivity in ileal neuroendocrine tumors are still lacking. Thirty-one consecutive, advanced primary midgut neuroendocrine tumors and related lymph node or liver metastases from 24 males and seven females were immunohistochemically assessed for SDHB. All patients were G1 tumors (Ki-67 labeling index ≤2%). SDHB immunohistochemistry results were expressed as immunostaining intensity and scored as low or strong according to the internal control represented by normal intestinal cells. Strong positivity for SDHB, with granular cytoplasmatic reactivity, was found in 77% of primary tumors (T), whilst low SDHB expression was detected in 90% of metastases (M). The combined analysis (T+M) confirmed the loss of SDHB expression in 82% of metastases compared to 18% of primary tumors. SDHB expression was inversely correlated with Ki-67 labeling index, which accounted for 1.54% in metastastic sites and 0.7% in primary tumors. A correlation between SDHB expression loss, increased Ki-67 labeling index and biological aggressiveness was shown in advanced midgut neuroendocrine tumors, suggesting a role of tumor suppressor gene.
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130
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Forbes JA, Brock AA, Ghiassi M, Thompson RC, Haynes DS, Tsai BS. Jugulotympanic paragangliomas: 75 years of evolution in understanding. Neurosurg Focus 2012; 33:E13. [DOI: 10.3171/2012.6.focus12138] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Jugulotympanic paragangliomas were first described approximately 75 years ago. Since that time, there has been considerable evolution in knowledge of tumor biology, methods of classification, and appropriate management strategies. This paper attempts to summarize these gains in information.
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Affiliation(s)
| | | | | | | | - David S. Haynes
- 3Department of Otolaryngology–Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Betty S. Tsai
- 3Department of Otolaryngology–Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
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131
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Fliedner SMJ, Kaludercic N, Jiang XS, Hansikova H, Hajkova Z, Sladkova J, Limpuangthip A, Backlund PS, Wesley R, Martiniova L, Jochmanova I, Lendvai NK, Breza J, Yergey AL, Paolocci N, Tischler AS, Zeman J, Porter FD, Lehnert H, Pacak K. Warburg effect's manifestation in aggressive pheochromocytomas and paragangliomas: insights from a mouse cell model applied to human tumor tissue. PLoS One 2012; 7:e40949. [PMID: 22859959 PMCID: PMC3409208 DOI: 10.1371/journal.pone.0040949] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Accepted: 06/19/2012] [Indexed: 12/17/2022] Open
Abstract
A glycolytic profile unifies a group of pheochromocytomas and paragangliomas (PHEOs/PGLs) with distinct underlying gene defects, including von Hippel-Lindau (VHL) and succinate dehydrogenase B (SDHB) mutations. Nevertheless, their tumor aggressiveness is distinct: PHEOs/PGLs metastasize rarely in VHL-, but frequently in SDHB-patients. To date, the molecular mechanisms causing the more aggressive phenotype in SDHB-PHEOs/PGLs remain largely unknown. Recently, however, an excellent model to study aggressive PHEOs (mouse tumor tissue (MTT) cells) has been developed from mouse PHEO cells (MPC). We employed this model for a proteomics based approach to identify changes characteristic for tumor aggressiveness, which we then explored in a homogeneous set of human SDHB- and VHL-PHEOs/PGLs. The increase of glucose transporter 1 in VHL, and of hexokinase 2 in VHL and SDHB, confirmed their glycolytic profile. In agreement with the cell model and in support of decoupling of glycolysis, the Krebs cycle and oxidative phosphorylation (OXPHOS), SDHB tumors showed increased lactate dehydrogenase levels. In SDHB-PGLs OXPHOS complex activity was increased at complex III and, as expected, decreased at complex II. Moreover, protein and mRNA expression of all tested OXPHOS-related genes were higher in SDHB- than in VHL-derived tumors. Although there was no direct evidence for increased reactive oxygen species production, elevated superoxide dismutase 2 expression may reflect elevated oxidative stress in SDHB-derived PHEOs/PGLs. For the first time, we show that despite dysfunction in complex II and evidence for a glycolytic phenotype, the Warburg effect does not seem to fully apply to SDHB-PHEOs/PGLs with respect to decreased OXPHOS. In addition, we present evidence for increased LDHA and SOD2 expression in SDHB-PHEOs/PGLs, proteins that have been proposed as promising therapeutic targets in other cancers. This study provides new insight into pathogenic mechanisms in aggressive human PHEOs/PGLs, which may lead to identifying new diagnostic and prognostic markers in the near future.
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Affiliation(s)
- Stephanie M. J. Fliedner
- Program in Reproductive and Adult Endocrinology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
- 1 Department of Medicine, University Hospitals of Schleswig-Holstein, Lübeck, Germany
| | - Nina Kaludercic
- Division of Cardiology, Department of Medicine, Johns Hopkins Medical Institutions, Baltimore, Maryland, United States of America
| | - Xiao-Sheng Jiang
- Section on Molecular Dysmorphology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Hana Hansikova
- Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Zuzana Hajkova
- Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Jana Sladkova
- Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Andrea Limpuangthip
- Program in Reproductive and Adult Endocrinology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Peter S. Backlund
- Section on Mass Spectrometry and Metabolism, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Robert Wesley
- Warren G. Magnuson Clinical Center, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Lucia Martiniova
- Program in Reproductive and Adult Endocrinology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Ivana Jochmanova
- Program in Reproductive and Adult Endocrinology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
- 1st Department of Internal Medicine Medical Faculty, P.J.Šafárik University, Košice, Slovakia
| | - Nikoletta K. Lendvai
- Program in Reproductive and Adult Endocrinology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Jan Breza
- Department of Urology, School of Medicine, Comenius University, Bratislava, Slovakia
| | - Alfred L. Yergey
- Section on Mass Spectrometry and Metabolism, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Nazareno Paolocci
- Division of Cardiology, Department of Medicine, Johns Hopkins Medical Institutions, Baltimore, Maryland, United States of America
- Department of Clinical Medicine, Section of Pathology, University of Perugia, Perugia, Italy
| | - Arthur S. Tischler
- Department of Pathology, Tufts Medical Center, Boston, Massachusetts, United States of America
| | - Jiri Zeman
- Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Forbes D. Porter
- Section on Molecular Dysmorphology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Hendrik Lehnert
- 1 Department of Medicine, University Hospitals of Schleswig-Holstein, Lübeck, Germany
| | - Karel Pacak
- Program in Reproductive and Adult Endocrinology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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132
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Neuzil J, Dong LF, Rohlena J, Truksa J, Ralph SJ. Classification of mitocans, anti-cancer drugs acting on mitochondria. Mitochondrion 2012; 13:199-208. [PMID: 22846431 DOI: 10.1016/j.mito.2012.07.112] [Citation(s) in RCA: 137] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Revised: 07/15/2012] [Accepted: 07/22/2012] [Indexed: 12/13/2022]
Abstract
Mitochondria have emerged as an intriguing target for anti-cancer drugs, inherent to vast majority if not all types of tumours. Drugs that target mitochondria and exert anti-cancer activity have become a focus of recent research due to their great clinical potential (which has not been harnessed thus far). The exceptional potential of mitochondria as a target for anti-cancer agents has been reinforced by the discouraging finding that even tumours of the same type from individual patients differ in a number of mutations. This is consistent with the idea of personalised therapy, an elusive goal at this stage, in line with the notion that tumours are unlikely to be treated by agents that target only a single gene or a single pathway. This endows mitochondria, an invariant target present in all tumours, with an exceptional momentum. This train of thoughts inspired us to define a class of anti-cancer drugs acting by way of mitochondrial 'destabilisation', termed 'mitocans'. In this communication, we define mitocans (many of which have been known for a long time) and classify them into several classes based on their molecular mode of action. We chose the targets that are of major importance from the point of view of their role in mitochondrial destabilisation by small compounds, some of which are now trialled as anti-cancer agents. The classification starts with targets at the surface of mitochondria and ending up with those in the mitochondrial matrix. The purpose of this review is to present in a concise manner the classification of compounds that hold a considerable promise as potential anti-cancer drugs.
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Affiliation(s)
- Jiri Neuzil
- School of Medical Science, Griffith University, Southport, Qld, Australia.
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133
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TCA Cycle Defects and Cancer: When Metabolism Tunes Redox State. Int J Cell Biol 2012; 2012:161837. [PMID: 22888353 PMCID: PMC3408673 DOI: 10.1155/2012/161837] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Revised: 06/01/2012] [Accepted: 06/15/2012] [Indexed: 12/17/2022] Open
Abstract
Inborn defects of the tricarboxylic acid (TCA) cycle enzymes have been known for more than twenty years. Until recently, only recessive mutations were described which, although resulted in severe multisystem syndromes, did not predispose to cancer onset. In the last ten years, a causal role in carcinogenesis has been documented for inherited and acquired alterations in three TCA cycle enzymes, succinate dehydrogenase (SDH), fumarate hydratase (FH), and isocitrate dehydrogenase (IDH), pointing towards metabolic alterations as the underlying hallmark of cancer. This paper summarizes the neoplastic alterations of the TCA cycle enzymes focusing on the generation of pseudohypoxic phenotype and the alteration of epigenetic homeostasis as the main tumor-promoting effects of the TCA cycle affecting defects. Moreover, we debate on the ability of these mutations to affect cellular redox state and to promote carcinogenesis by impacting on redox biology.
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134
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Zheleznova NN, Yang C, Ryan RP, Halligan BD, Liang M, Greene AS, Cowley AW. Mitochondrial proteomic analysis reveals deficiencies in oxygen utilization in medullary thick ascending limb of Henle in the Dahl salt-sensitive rat. Physiol Genomics 2012; 44:829-42. [PMID: 22805345 DOI: 10.1152/physiolgenomics.00060.2012] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The renal medullary thick ascending limb (mTAL) of the Dahl salt-sensitive (SS) rat is the site of enhanced NaCl reabsorption and excess superoxide production. In the present studies we isolated mitochondria from mTAL of SS and salt-resistant control strain SS.13(BN) rats on 0.4 and 8% salt diet for 7 days and performed a proteomic analysis. Purity of mTAL and mitochondria isolations exceeded 93.6 and 55%, respectively. Using LC/MS spectral analysis techniques we identified 96 mitochondrial proteins in four biological mTAL mitochondria samples, run in duplicate, as defined by proteins with a false discovery rate <5% and scan count ≥2. Seven of these 96 proteins, including IDH2, ACADM, SCOT, Hsp60, ATPA, EFTu, and VDAC2 were differentially expressed between the two rat strains. Oxygen consumption and high-resolution respirometry analyses showed that mTAL cells and the mitochondria in the outer medulla of SS rats fed high-salt diet exhibited lower rates of oxygen utilization compared with those from SS.13(BN) rats. These studies advance the conventional proteomic paradigm of focusing exclusively upon whole tissue homogenates to a focus upon a single cell type and specific subcellular organelle. The results reveal the importance of a largely unexplored role for deficiencies of mTAL mitochondrial metabolism and oxygen utilization in salt-induced hypertension and renal medullary oxidative stress.
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Affiliation(s)
- Nadezhda N Zheleznova
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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135
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Chen JQ, Russo J. Dysregulation of glucose transport, glycolysis, TCA cycle and glutaminolysis by oncogenes and tumor suppressors in cancer cells. Biochim Biophys Acta Rev Cancer 2012; 1826:370-84. [PMID: 22750268 DOI: 10.1016/j.bbcan.2012.06.004] [Citation(s) in RCA: 150] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Revised: 06/16/2012] [Accepted: 06/18/2012] [Indexed: 12/19/2022]
Abstract
A common set of functional characteristics of cancer cells is that cancer cells consume a large amount of glucose, maintain high rate of glycolysis and convert a majority of glucose into lactic acid even in the presence of oxygen compared to that of normal cells (Warburg's Effects). In addition, cancer cells exhibit substantial alterations in several energy metabolism pathways including glucose transport, tricarboxylic acid (TCA) cycle, glutaminolysis, mitochondrial respiratory chain oxidative phosphorylation and pentose phosphate pathway (PPP). In the present work, we focused on reviewing the current knowledge about the dysregulation of the proteins/enzymes involved in the key regulatory steps of glucose transport, glycolysis, TCA cycle and glutaminolysis by several oncogenes including c-Myc and hypoxia inducible factor-1 (HIF-1) and tumor suppressor, p53, in cancer cells. The dysregulation of glucose transport and energy metabolism pathways by oncogenes and lost functions of the tumor suppressors have been implicated as important biomarkers for cancer detection and as valuable targets for the development of new anticancer therapies.
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Affiliation(s)
- Jin-Qiang Chen
- Breast Cancer Research Laboratory, Fox Chase Cancer Center, Philadelphia, PA 19111, USA.
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136
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Schaffer S, Asseburg H, Kuntz S, Muller WE, Eckert GP. Effects of polyphenols on brain ageing and Alzheimer's disease: focus on mitochondria. Mol Neurobiol 2012; 46:161-78. [PMID: 22706880 DOI: 10.1007/s12035-012-8282-9] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Accepted: 05/24/2012] [Indexed: 02/07/2023]
Abstract
The global trend of the phenomenon of population ageing has dramatic consequences on public health and the incidence of neurodegenerative diseases. Physiological changes that occur during normal ageing of the brain may exacerbate and initiate pathological processes that may lead to neurodegenerative disorders, especially Alzheimer's disease (AD). Hence, the risk of AD rises exponentially with age. While there is no cure currently available, sufficient intake of certain micronutrients and secondary plant metabolites may prevent disease onset. Polyphenols are highly abundant in the human diet, and several experimental and epidemiological evidences indicate that these secondary plant products have beneficial effects on AD risks. This study reviews current knowledge on the potential of polyphenols and selected polyphenol-rich diets on memory and cognition in human subjects, focusing on recent data showing in vivo efficacy of polyphenols in preventing neurodegenerative events during brain ageing and in dementia. Concentrations of polyphenols in animal brains following oral administration have been consistently reported to be very low, thus eliciting controversial discussion on their neuroprotective effects and potential mechanisms. Whether polyphenols exert any direct antioxidant effects in the brain or rather act by evoking alterations in regulatory systems of the brain or even the body periphery is still unclear. To understand the mechanisms behind the protective abilities of polyphenol-rich foods, an overall understanding of the biotransformation of polyphenols and identification of the various metabolites arising in the human body is also urgently needed.
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Affiliation(s)
- Sebastian Schaffer
- Department of Biochemistry, Centre for Life Sciences, National University of Singapore, 22 Medical Drive, Singapore 117456, Singapore
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137
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Rapizzi E, Ercolino T, Canu L, Giaché V, Francalanci M, Pratesi C, Valeri A, Mannelli M. Mitochondrial function and content in pheochromocytoma/paraganglioma of succinate dehydrogenase mutation carriers. Endocr Relat Cancer 2012; 19:261-9. [PMID: 22323561 DOI: 10.1530/erc-11-0263] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
To date, the consequences of succinate dehydrogenase (SDH) impairment on overall mitochondrial functions are still obscure. In this study, we evaluated SDH activity and expression and mitochondrial homeostasis in 57 tissue samples of pheochromocytoma (PHEO)/paraganglioma (PGL) obtained from patients genotyped for PHEO/PGL susceptibility genes. The resulted SDH activity and content always decreased in SDH-mutated tumors, in one out of two MAX-mutated patients and in four patients resulted wild type (wt) at genetic screening. All these four wt patients were further screened for large deletions in SDH genes, TMEM127 and MAX and resulted wt but two had somatic SDHD mutations. The RT-PCR in the MAX-mutated sample suggests that the decrease in SDH depends on complex instability and not on a reduced SDHB expression. SDH mutations neither alter citrate synthase (CS) activity nor the content of voltage-dependent anion channel (VDAC) while the expression of the mitochondrial complex IV (cytochrome c oxidase (COX)) was found extremely variable in all (mutated and wt) samples suggesting an impairment of mitochondrial cristae in these tumors. In conclusion, tumors from patients with germ line SDH mutations invariably show decreased enzymatic activity and content, but an SDH impairment may also depend on SDH somatic mutations or, seemingly, on MAX mutations. The impaired SDH activity in the two wt tissues suggests mutations in other still unknown susceptibility genes. Finally, the extreme variability in COX expression levels is yet to be explained and this strongly suggests to evaluate other mitochondrial features to better understand the mitochondrial role in the pathogenesis of these tumors.
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Affiliation(s)
- E Rapizzi
- Endocrinology Unit, Department of Clinical Pathophysiology, University of Florence, Viale Pieraccini 6, 50139 Florence, Italy
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138
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Eckert GP, Renner K, Eckert SH, Eckmann J, Hagl S, Abdel-Kader RM, Kurz C, Leuner K, Muller WE. Mitochondrial Dysfunction—A Pharmacological Target in Alzheimer's Disease. Mol Neurobiol 2012; 46:136-50. [DOI: 10.1007/s12035-012-8271-z] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2012] [Accepted: 04/16/2012] [Indexed: 12/12/2022]
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139
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Saito Y, Tanaka Y, Aita Y, Ishii KA, Ikeda T, Isobe K, Kawakami Y, Shimano H, Hara H, Takekoshi K. Sunitinib induces apoptosis in pheochromocytoma tumor cells by inhibiting VEGFR2/Akt/mTOR/S6K1 pathways through modulation of Bcl-2 and BAD. Am J Physiol Endocrinol Metab 2012; 302:E615-25. [PMID: 21878661 DOI: 10.1152/ajpendo.00035.2011] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Sunitinib is an oral multitargeted receptor tyrosine kinase inhibitor with antiangiogenic and antitumor activity that mainly targets vascular endothelial growth factor receptors (VEGFRs). Very recently, sunitinib has been shown to be an active agent for the treatment of malignant pheochromocytomas. However, it is unclear whether sunitinib acts only through an antiangiogenic mechanism or whether it may also directly target tumor cells. Sunitinib markedly induced apoptosis of PC12 cells in a dose-dependent and time-dependent manner. Furthermore, in support of these findings, we found that sunitinib induced a reduction in the expression of the antiapoptotic molecule Bcl-2 as well as dephosphorylation of the proapoptotic molecule BAD, which results in the activation of BAD in these cells. Consistent with these apoptotic effects, our results showed that sunitinib inhibited phosphorylation of Akt and mTOR and was followed by a reduction of S6K1, which is a well-known target of mTOR. Knockdown of VEGFR-2 attenuated the sunitinib-induced effects, including apoptosis and inhibition of signaling pathways such as the phosphorylation of Akt as well as mTOR, and Bcl-2, which confirmed that these effects could be mediated by VEGFR-2. In addition, silencing of S6K1 induced apoptosis accompanied by a decrease in the phosphorylation of BAD and Bcl-2, similar to that observed with sunitinib treatment. Thus, these results together suggest that sunitinib initially exerts its apoptotic effect through the inhibition of VEGFR-2, which, when followed by reduction of its downstream effectors, including Akt/mTOR/S6K1, may lead to inhibition of the antiapoptotic molecule Bcl-2 and activation of the proapoptotic molecule BAD in PC12 cells. However, PC12 cells do not precisely reflect the pathogenesis of malignant cells. Therefore, we confirmed the key findings by replicating these experiments in human neuroblastoma SK-N-SH cells.
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Affiliation(s)
- Yuria Saito
- Department of Laboratory Medicine, Graduate School of Comprehensive Human Sciences, University of Tskuba, Ibaraki, Japan
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140
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Paddenberg R, Tiefenbach M, Faulhammer P, Goldenberg A, Gries B, Pfeil U, Lips KS, Piruat JI, López-Barneo J, Schermuly RT, Weissmann N, Kummer W. Mitochondrial complex II is essential for hypoxia-induced pulmonary vasoconstriction of intra- but not of pre-acinar arteries. Cardiovasc Res 2012; 93:702-10. [DOI: 10.1093/cvr/cvr359] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
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141
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Owens KM, Aykin-Burns N, Dayal D, Coleman MC, Domann FE, Spitz DR. Genomic instability induced by mutant succinate dehydrogenase subunit D (SDHD) is mediated by O2(-•) and H2O2. Free Radic Biol Med 2012; 52:160-6. [PMID: 22041456 PMCID: PMC3249516 DOI: 10.1016/j.freeradbiomed.2011.10.435] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Revised: 10/04/2011] [Accepted: 10/06/2011] [Indexed: 01/24/2023]
Abstract
SDHD mutations are associated with human cancers but the mechanisms that may contribute to transformation are unknown. The hypothesis that mutations in SDHD increase levels of superoxide leading to genomic instability was tested using site-directed mutagenesis to generate a truncated SDHD cDNA that was expressed in Chinese hamster fibroblasts. Stable expression of mutant SDHD resulted in 2-fold increases in steady-state levels of superoxide that were accompanied by a significantly increased mutation rate as well as a 70-fold increase in mutation frequency at the hprt locus. Overexpression of MnSOD or treatment with polyethylene glycol conjugated (PEG)-catalase suppressed mutation frequency in SDHD mutant cells by 50% (P<0.05). Simultaneous treatment with PEG-catalase and PEG-SOD suppressed mutation frequency in SDHD mutant cells by 90% (P<0.0005). Finally, 95% depletion of glutathione using l-buthionine-[S,R]-sulfoximine (BSO) in SDHD mutant cells caused a 4-fold increase in mutation frequency (P<0.05). These results demonstrate that mutations in SDHD cause increased steady-state levels of superoxide which significantly contributed to increases in mutation rates and frequency mediated by superoxide and hydrogen peroxide. These results support the hypothesis that mutations in SDHD may contribute to carcinogenesis by increasing genomic instability mediated by increased steady-state levels of reactive oxygen species.
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Affiliation(s)
- Kjerstin M. Owens
- Free Radical and Radiation Biology Program, Department of Radiation Oncology, Holden Comprehensive Cancer Center, The University of lowa, lowa City, lowa 52242
- Current Address: Dr. Kjerstin M. Owens, Trocaire College, 360 Choate Ave, Buffalo, NY 14220-2094
| | - Nōkhet Aykin-Burns
- Free Radical and Radiation Biology Program, Department of Radiation Oncology, Holden Comprehensive Cancer Center, The University of lowa, lowa City, lowa 52242
| | - Disha Dayal
- Free Radical and Radiation Biology Program, Department of Radiation Oncology, Holden Comprehensive Cancer Center, The University of lowa, lowa City, lowa 52242
- Current Address: Dr. Disha Dayal, Cactus Communications, 510 Shalimar Morya Park, Andheri (West), Mumbai, India 400053
| | - Mitchell C. Coleman
- Free Radical and Radiation Biology Program, Department of Radiation Oncology, Holden Comprehensive Cancer Center, The University of lowa, lowa City, lowa 52242
| | - Frederick E. Domann
- Free Radical and Radiation Biology Program, Department of Radiation Oncology, Holden Comprehensive Cancer Center, The University of lowa, lowa City, lowa 52242
| | - Douglas R. Spitz
- Free Radical and Radiation Biology Program, Department of Radiation Oncology, Holden Comprehensive Cancer Center, The University of lowa, lowa City, lowa 52242
- Corresponding author: Douglas R Spitz, PhD B180 Medical Laboratories The University of lowa lowa City, IA 52242, Telephone: 319-335-8001 Fax: 319-335-8039,
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142
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Korevaar TIM, Grossman AB. Pheochromocytomas and paragangliomas: assessment of malignant potential. Endocrine 2011; 40:354-65. [PMID: 22038451 DOI: 10.1007/s12020-011-9545-3] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Accepted: 09/16/2011] [Indexed: 12/23/2022]
Abstract
Pheochromocytomas and paragangliomas (PPGLs) are rare catecholamine-secreting tumors which arise from the adrenal glands or sympathetic neuronal tissue. Malignant transformation of these tumors occurs in a significant proportion and may therefore lower overall survival rates. In patients with PPGLs it is impossible to identify malignant disease without the presence of metastatic disease, something which can occur as long as 20 years after initial surgery. Early identification of malignant disease would necessitate a more aggressive treatment approach, something which may result in better disease outcome. We have therefore reviewed possible predictors of malignancy and current developments in order to help clinicians to swiftly assess malignant potential in patients with PPGLs. Currently, there is no absolute marker which can objectively reflect malignant potential. Tumor size is the most reliable predictor and should therefore be used as the baseline characteristic. The combination of various clinical markers (extra-adrenal disease and post-operative hypertension), biochemical markers (high dopamine, high norepinephrine and epinephrine to total catecholamine ratio) and/or histological markers (SNAIL, microRNAs and/or microarray results) can raise or lower the suspicion of malignancy. Furthermore, we discuss how clinical markers may affect biochemical results linked to malignancy, how biochemical results may distinguish hereditary syndromes, the role of imaging in determining malignant potential and tumor detection, and recent results of proposed histological markers.
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Affiliation(s)
- Tim I M Korevaar
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Headington, Oxford, OX3 7LE, UK
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143
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Welander J, Söderkvist P, Gimm O. Genetics and clinical characteristics of hereditary pheochromocytomas and paragangliomas. Endocr Relat Cancer 2011; 18:R253-76. [PMID: 22041710 DOI: 10.1530/erc-11-0170] [Citation(s) in RCA: 259] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Pheochromocytomas (PCCs) and paragangliomas (PGLs) are rare neuroendocrine tumors of the adrenal glands and the sympathetic and parasympathetic paraganglia. They can occur sporadically or as a part of different hereditary tumor syndromes. About 30% of PCCs and PGLs are currently believed to be caused by germline mutations and several novel susceptibility genes have recently been discovered. The clinical presentation, including localization, malignant potential, and age of onset, varies depending on the genetic background of the tumors. By reviewing more than 1700 reported cases of hereditary PCC and PGL, a thorough summary of the genetics and clinical features of these tumors is given, both as part of the classical syndromes such as multiple endocrine neoplasia type 2 (MEN2), von Hippel-Lindau disease, neurofibromatosis type 1, and succinate dehydrogenase-related PCC-PGL and within syndromes associated with a smaller fraction of PCCs/PGLs, such as Carney triad, Carney-Stratakis syndrome, and MEN1. The review also covers the most recently discovered susceptibility genes including KIF1Bβ, EGLN1/PHD2, SDHAF2, TMEM127, SDHA, and MAX, as well as a comparison with the sporadic form. Further, the latest advances in elucidating the cellular pathways involved in PCC and PGL development are discussed in detail. Finally, an algorithm for genetic testing in patients with PCC and PGL is proposed.
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Affiliation(s)
- Jenny Welander
- Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, 58185 Linköping, Sweden
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144
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Kaelin WG. Cancer and altered metabolism: potential importance of hypoxia-inducible factor and 2-oxoglutarate-dependent dioxygenases. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2011; 76:335-45. [PMID: 22089927 DOI: 10.1101/sqb.2011.76.010975] [Citation(s) in RCA: 133] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Hypoxia-inducible factor (HIF) deregulation contributes to the Warburg effect. HIF consists of an unstable α subunit and a stable β subunit. In the presence of oxygen, HIFα becomes prolyl hydroxylated by members of the EglN (also called PHD) family, leading to its proteasomal degradation. Under hypoxic conditions, EglN activity is diminished and HIF levels rise. EglN1 is the primary HIF prolyl hydroxylase with EglN2 and EglN3 playing compensatory roles under certain conditions. EglN2 and EglN3 also appear to play HIF-independent roles in regulating cell proliferation and apoptosis, respectively. The EglNs belong to a large family of 2-oxoglutarate-dependent dioxygenases that includes the TET DNA hydroxymethylases and JmjC-containing histone demethylases. Members of this superfamily can be inhibited by endogenous metabolites, including fumarate and succinate, which accumulate in tumors that have fumarate hydratase (FH) or succinate dehydrogenase (SDH) mutations, respectively, as well as by the 2-hydroxyglutarate detected in isocitrate dehydrogenase (IDH) mutant tumors. 2-Oxoglutarate-dependent dioxygenases therefore provide a link between altered metabolism and cancer.
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Affiliation(s)
- W G Kaelin
- Howard Hughes Medical Institute, Dana-Farber Cancer Institute and Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02215, USA.
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145
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Miettinen M, Wang ZF, Sarlomo-Rikala M, Osuch C, Rutkowski P, Lasota J. Succinate dehydrogenase-deficient GISTs: a clinicopathologic, immunohistochemical, and molecular genetic study of 66 gastric GISTs with predilection to young age. Am J Surg Pathol 2011; 35:1712-21. [PMID: 21997692 PMCID: PMC3193596 DOI: 10.1097/pas.0b013e3182260752] [Citation(s) in RCA: 273] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Most gastrointestinal stromal tumors (GISTs) are driven by KIT or PDGFRA-activating mutations, but a small subset is associated with loss of function of the succinate dehydrogenase (SDH) complex of mitochondrial inner membrane proteins. This occurs by germline mutations of the SDH subunit genes and hitherto unknown mechanisms. SDH-deficient GISTs especially include pediatric GISTs and those associated with Carney triad (CT) or Carney-Stratakis syndromes (CSSs); the latter 2 also include paraganglioma as a component. SDH-deficient GISTs were identified in this study on the basis of immunohistochemical loss of succinate dehydrogenase subunit B (SDHB), which signals functional loss of the SDH complex. We found 66 SDH-deficient GISTs among 756 gastric GISTs, with an estimated frequency of 7.5% of unselected cases. Nearly, all gastric GISTs in patients <20 years, and a substantial percentage of those in patients <40 years, but only rare GISTs in older adults were SDH deficient. There was a female predominance of over 2:1. Two patients each had either pulmonary chondroma or paraganglioma (CT), but none of the examined cases had SDH germline mutations (CSS) or somatic KIT/PDGFRA or BRAF mutations. SDH-deficient GISTs were often multiple and typically showed plexiform muscularis propria involvement and epithelioid hypercellular morphology. They were consistently KIT-positive and DOG1/Ano 1-positive and almost always smooth muscle actin negative. Tumor size and mitotic activity varied, and the tumors were somewhat unpredictable with low mitotic rates developing metastases. Gastric recurrences occurred in 11 patients, and peritoneal and liver metastases occurred in 8 and 10 patients, respectively. Lymph node metastases were detected in 5 patients, but lymphovascular invasion was present in >50% of cases studied; these 2 were not related to adverse outcome. Seven patients died of disease, but many had long survivals, even with peritoneal or liver metastases. All 378 nongastric GISTs and 34 gastric non-GIST mesenchymal tumors were SDHB positive. SDH-deficient GISTs constitute a small subgroup of gastric GISTs; they usually occur in children and young adults, often have a chronic course similar to that of pediatric and CT GISTs, and have potential association with paraganglioma, necessitating long-term follow-up.
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Affiliation(s)
- Markku Miettinen
- Laboratory of Pathology, National Cancer Institute, Bethesda, 20892, USA.
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146
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Ishii T, Miyazawa M, Hartman PS, Ishii N. Mitochondrial superoxide anion (O(2)(-)) inducible "mev-1" animal models for aging research. BMB Rep 2011; 44:298-305. [PMID: 21615983 DOI: 10.5483/bmbrep.2011.44.5.298] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Most intracellular reactive oxygen species (ROS), especially superoxide anion (O(2)(-)) that is converted from oxygen, are overproduced by excessive electron leakage from the mitochondrial respiratory chain. Intracellular oxidative stress that damages cellular components can contribute to lifestyle-related diseases such as diabetes and arteriosclerosis, and age-related diseases such as cancer and neuronal degenerative diseases. We have previously demonstrated that the excessive mitochondrial O(2)(-) production caused by SDHC mutations (G71E in C. elegans, I71E in Drosophila and V69E in mouse) results in premature death in C. elegans and Drosophila, cancer in mouse embryonic fibroblast cells and infertility in transgenic mice. SDHC is a subunit of mitochondrial complex II. In humans, it has been reported that mutations in SDHB, SDHC or SDHD often result in inherited head and neck paragangliomas (PGLs). Recently, we established Tet-mev-1 conditional transgenic mice using our uniquely developed Tet-On/Off system, which equilibrates transgene expression to endogenous levels. These mice experienced mitochondrial respiratory chain dysfunction that resulted in O(2)(-) overproduction. The mitochondrial oxidative stress caused excessive apoptosis leading to low birth weight and growth retardation in the neonatal developmental phase in Tet-mev-1 mice. Here, we briefly describe the relationships between mitochondrial O(2)(-) and aging phenomena in mev-1 animal models. [BMB reports 2011; 44(5): 298-305].
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Affiliation(s)
- Takamasa Ishii
- Department of Molecular Life Science, Basic Medical Science and Molecular Medicine, Tokai University School of Medicine, Shimokasuya, Isehara, Kanagawa, Japan.
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147
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Cyr AR, Domann FE. The redox basis of epigenetic modifications: from mechanisms to functional consequences. Antioxid Redox Signal 2011; 15:551-89. [PMID: 20919933 PMCID: PMC3118659 DOI: 10.1089/ars.2010.3492] [Citation(s) in RCA: 194] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Epigenetic modifications represent mechanisms by which cells may effectively translate multiple signaling inputs into phenotypic outputs. Recent research is revealing that redox metabolism is an increasingly important determinant of epigenetic control that may have significant ramifications in both human health and disease. Numerous characterized epigenetic marks, including histone methylation, acetylation, and ADP-ribosylation, as well as DNA methylation, have direct linkages to central metabolism through critical redox intermediates such as NAD(+), S-adenosyl methionine, and 2-oxoglutarate. Fluctuations in these intermediates caused by both normal and pathologic stimuli may thus have direct effects on epigenetic signaling that lead to measurable changes in gene expression. In this comprehensive review, we present surveys of both metabolism-sensitive epigenetic enzymes and the metabolic processes that may play a role in their regulation. To close, we provide a series of clinically relevant illustrations of the communication between metabolism and epigenetics in the pathogenesis of cardiovascular disease, Alzheimer disease, cancer, and environmental toxicity. We anticipate that the regulatory mechanisms described herein will play an increasingly large role in our understanding of human health and disease as epigenetics research progresses.
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Affiliation(s)
- Anthony R Cyr
- Free Radical and Radiation Biology Program, Department of Radiation Oncology, Carver College of Medicine, The University of Iowa, Iowa City, Iowa 52242-1181, USA
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148
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Bardella C, Pollard PJ, Tomlinson I. SDH mutations in cancer. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1807:1432-43. [PMID: 21771581 DOI: 10.1016/j.bbabio.2011.07.003] [Citation(s) in RCA: 273] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Revised: 06/28/2011] [Accepted: 07/03/2011] [Indexed: 01/30/2023]
Abstract
The SDHA, SDHB, SDHC, SDHD genes encode the four subunits of succinate dehydrogenase (SDH; mitochondrial complex II), a mitochondrial enzyme involved in two essential energy-producing metabolic processes of the cell, the Krebs cycle and the electron transport chain. Germline loss-of-function mutations in any of the SDH genes or assembly factor (SDHAF2) cause hereditary paraganglioma/phaeochromocytoma syndrome (HPGL/PCC) through a mechanism which is largely unknown. Owing to the central function of SDH in cellular energy metabolism it is important to understand its role in tumor suppression. Here is reported an overview of genetics, clinical and molecular progress recently performed in understanding the basis of HPGL/PCC tumorigenesis.
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Affiliation(s)
- Chiara Bardella
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK
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149
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Abstract
BACKGROUND Paragangliomas in the region of the thyroid gland are rare tumors that can present a diagnostic challenge by mimicking follicular and c-cell derived thyroid tumors. SUMMARY Thyroid-associated paragangliomas are likely a subset of laryngeal paragangliomas and, although quite rare, should be considered in the differential diagnosis of a hypervascular thyroid nodule. The preoperative diagnosis of thyroid-associated paragangliomas can be challenging since the cytologic and histologic features overlap with more common primary thyroid neoplasms, in particular medullary carcinoma. Differential expression of a panel of immunohistochemical markers, including neuro-specific enolase, chromogranin A, synaptophysin, keratin, and S100, can be used to distinguish thyroid-associated paragangliomas from primary thyroid tumors. Intraoperatively, thyroid-associated paragangliomas may be associated with significant intraoperative bleeding and are often densely adherent to surrounding tissues, including the recurrent laryngeal nerve. Interestingly, the aggressive local behavior of these tumors does not correspond to potential for malignancy, as there are no patients with malignant thyroid-associated paragangliomas reported in the medical literature. Therefore, these tumors may be treated with limited resection. Postoperatively, patients with paragangliomas should receive hormonal evaluation for functional disease, imaging evaluation for multicentric and metastatic disease, and genetic counseling. CONCLUSION Thyroid-associated paragangliomas are an important part of the differential diagnosis of a hypervascular thyroid nodule, especially in a patient with a fine-needle aspiration biopsy suggestive of medullary thyroid carcinoma, but with unremarkable serum calcitonin levels. Consideration of a thyroid-associated paraganglioma also has important operative and postoperative implications for determining the extent of thyroid resection as well as follow-up testing.
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Affiliation(s)
- Roy Phitayakorn
- Department of Surgery, The Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA.
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150
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Abstract
Mutations in cancer cells affecting subunits of the respiratory chain (RC) indicate a central role of oxidative phosphorylation for tumourigenesis. Recent studies have suggested that such mutations of RC complexes impact apoptosis induction. We review here the evidence for this hypothesis, which in particular emerged from work on how complex I and II mediate signals for apoptosis. Both protein aggregates are specifically inhibited for apoptosis induction through different means by exploiting with protease activation and pH change, two widespread but independent features of dying cells. Nevertheless, both converge on forming reactive oxygen species for the demise of the cell. Investigations into these mitochondrial processes will remain a rewarding area for unravelling the causes of tumourigenesis and for discovering interference options.
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