501
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Abstract
A constant supply of oxygen is indispensable for cardiac viability and function. However, the role of oxygen and oxygen-associated processes in the heart is complex, and they and can be either beneficial or contribute to cardiac dysfunction and death. As oxygen is a major determinant of cardiac gene expression, and a critical participant in the formation of ROS and numerous other cellular processes, consideration of its role in the heart is essential in understanding the pathogenesis of cardiac dysfunction.
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Affiliation(s)
- Frank J Giordano
- Department of Medicine, Yale University School of Medicine, New Haven, Connecticut 06510, USA.
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502
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Abstract
A constant supply of oxygen is indispensable for cardiac viability and function. However, the role of oxygen and oxygen-associated processes in the heart is complex, and they and can be either beneficial or contribute to cardiac dysfunction and death. As oxygen is a major determinant of cardiac gene expression, and a critical participant in the formation of ROS and numerous other cellular processes, consideration of its role in the heart is essential in understanding the pathogenesis of cardiac dysfunction.
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Affiliation(s)
- Frank J Giordano
- Department of Medicine, Yale University School of Medicine, New Haven, Connecticut 06510, USA.
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503
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Kivela AJ, Parkkila S, Saarnio J, Karttunen TJ, Kivela J, Parkkila AK, Bartosova M, Mucha V, Novak M, Waheed A, Sly WS, Rajaniemi H, Pastorekova S, Pastorek J. Expression of von Hippel-Lindau tumor suppressor and tumor-associated carbonic anhydrases IX and XII in normal and neoplastic colorectal mucosa. World J Gastroenterol 2005; 11:2616-25. [PMID: 15849821 PMCID: PMC4305753 DOI: 10.3748/wjg.v11.i17.2616] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To analyze possible relationships between CA IX/CA XII and pVHL expression in normal and neoplastic colorectal mucosa.
METHODS: Immunohistochemical staining of 42 tissue specimens obtained from 17 cancer patients was performed to evaluate the distribution and semi-quantitatively assess the levels of CA IX, CA XII and pVHL. VHL mRNAs from 14 fresh-frozen tumors was amplified by RT-PCR and subjected to sequencing. CA9 and CA12 mRNA levels were analyzed by semi-quantitative RT-PCR in comparison with VEGF as an indicator of hypoxia that uncouples the pVHL control.
RESULTS: Tumor tissues were associated with a borderline increase of CA IX staining signal and slight but significant decrease of CA XII immunoreactivity, whereas no association was found for pVHL. Sequence analysis of RT-PCR-amplified VHL mRNAs revealed no deletions/mutations, suggesting that they were VHL-competent. We did not observe any correlation between pVHL and CA IX/CA XII proteins as well as between VEGF and CA9 mRNAs, but the tumor-associated changes in mRNA levels of VEGF and CA12 showed a significant inverse relationship.
CONCLUSION: Our results indicate that CA9 and CA12 are regulated by different intratumoral factors and that lack of apparent relationship between the levels of CA IX/CA XII and pVHL cannot be fully assigned to uncoupling of negative regulatory function of pVHL by tumor hypoxia signified by induced VEGF transcription. The interplay between the functional pVHL and CA IX/CA XII in colorectal tumors seems rather complex and is not evident merely at the expression levels.
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Affiliation(s)
- Antti-J Kivela
- Department of Anatomy and Cell Biology, University of Oulu, Finland
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504
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Haase VH. The VHL tumor suppressor in development and disease: functional studies in mice by conditional gene targeting. Semin Cell Dev Biol 2005; 16:564-74. [PMID: 15908240 PMCID: PMC3787877 DOI: 10.1016/j.semcdb.2005.03.006] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The von Hippel-Lindau tumor suppressor pVHL plays a critical role in the pathogenesis of familial and sporadic clear cell carcinomas of the kidney and hemangioblastomas of the retina and central nervous system. pVHL targets the oxygen sensitive alpha subunit of hypoxia-inducible factor (HIF) for proteasomal degradation, thus providing a direct link between tumorigenesis and molecular pathways critical for cellular adaptation to hypoxia. Cell type specific gene targeting of VHL in mice has demonstrated that proper pVHL mediated HIF proteolysis is fundamentally important for survival, proliferation and differentiation of many cell types and furthermore, that inactivation of pVHL may, unexpectedly, inhibit tumor growth under certain conditions. Mouse knock out studies have provided novel mechanistic insights into VHL associated tumorigenesis and established a central role for HIF in the development of the VHL phenotype.
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Affiliation(s)
- Volker H Haase
- Department of Medicine, University of Pennsylvania School of Medicine, 700 CRB, 415 Curie Boulevard, Philadelphia, PA 19104-6144, USA.
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505
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Abstract
The transcription factor hypoxia-inducible factor-1 (HIF) is commonly activated in cancer. This has major effects on gene expression, and is important in tumor angiogenesis. Besides being activated by low oxygen, genetic events in cancer contribute to activating HIF. Most striking is that loss of function of the VHL tumour suppressor protein results in constitutive activation of the HIF pathway. An important aim is to define the contribution of HIF activation to the evolution of different cancers, and its potential as a therapeutic target.
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Affiliation(s)
- Patrick H Maxwell
- Renal Section, Hammersmith Campus, Imperial College London, Du Cane Road, London W12 0NN, UK.
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506
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Zdravkovic T, Genbacev O, McMaster MT, Fisher SJ. The adverse effects of maternal smoking on the human placenta: A review. Placenta 2005; 26 Suppl A:S81-6. [PMID: 15837073 DOI: 10.1016/j.placenta.2005.02.003] [Citation(s) in RCA: 159] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/03/2005] [Indexed: 11/18/2022]
Abstract
Studies of placental pathologies associated with maternal cigarette smoking have led to many interesting observations. For example, maternal smoking impairs human placental development by changing the balance between cytotrophoblast (CTB) proliferation and differentiation. It is likely that chronic exposure to tobacco constituents in early pregnancy can affect placental development directly or indirectly by reducing blood flow, which creates a pathologically hypoxic environment. To understand this process at a molecular level, tissue samples from non-smoking and smoking mothers were studied to determine whether active and/or passive cigarette smoke exposure affects CTB expression of molecules that govern cellular responses to oxygen tension: the von Hippel-Lindau tumor suppressor protein (pVHL), hypoxia-inducible transcription factors (HIFs) and vascular endothelial growth factor-A (VEGF). The results show that maternal smoking dysregulates CTB expression of all three types of molecules. In addition, cell columns and proliferating cells were reduced while there was a corresponding increase in cell islands. All three phenomena were most obvious in the placentas of heavy smokers. Interestingly, a subset of the aforementioned effects can be detected in samples obtained from women who were passively exposed to cigarette smoke during pregnancy. These observations suggest that tobacco constituents exert direct effects on CTB proliferation and differentiation and help to explain the mechanisms by which smoking negatively effects human pregnancy outcome.
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Affiliation(s)
- T Zdravkovic
- Department of Cell and Tissue Biology, University of California San Francisco, 513 Parnassus Avenue, San Francisco, CA 94143-0512, USA
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507
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Affiliation(s)
- Alfred L Goldberg
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
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508
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Hägg M, Wennström S. Activation of hypoxia-induced transcription in normoxia. Exp Cell Res 2005; 306:180-91. [PMID: 15878343 DOI: 10.1016/j.yexcr.2005.01.017] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2004] [Revised: 01/20/2005] [Accepted: 01/31/2005] [Indexed: 12/20/2022]
Abstract
Hypoxia-inducible factor-1 (HIF-1), the master regulator of transcriptional responses to reduced oxygen tension (hypoxia) in mammalian cells, consists of one HIF-1alpha and one HIF-1beta subunit. In normoxia, HIF-1alpha subunits are hydroxylated on specific proline residues; modifications that signal ubiquitination and degradation of HIF-1alpha by the proteasome. To test the effect of saturating HIF-1alpha degradation, we generated a construct, denoted the saturating domain (SD), based on a region surrounding proline 564 (Pro564) in HIF-1alpha. Expression of the SD led to accumulation of endogenous HIF-1alpha proteins in nuclei of normoxic cells. The induced HIF-1alpha was functional as it activated expression from a hypoxia-regulated reporter gene and from the endogenous vascular endothelial growth facor-a (Vegf-a) and carbonic anhydrase 9 (Ca9) genes. The effect of the SD was dependent on Pro564 since a mutated SD, in which Pro564 had been replaced by a glycine residue, failed to bind the von Hippel-Lindau protein (pVHL) and to stabilise HIF-1alpha. Treatment of cells with the prolylhydroxylase inhibitor dimethyloxalylglycine, or the proteasome inhibitor MG-132, mimicked the effect of the SD. In conclusion, we show that blocking HIF-1alpha degradation, either by saturation, or inhibition of prolyl hydroxylases or proteosomal degradation, leads to nuclear localisation of active HIF-1alpha proteins.
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Affiliation(s)
- Maria Hägg
- Department of Genetics and Pathology, Rudbeck Laboratory, Dag Hammarskjölds väg 20, S-751 85 Uppsala, Sweden
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509
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Couvelard A, O'Toole D, Turley H, Leek R, Sauvanet A, Degott C, Ruszniewski P, Belghiti J, Harris AL, Gatter K, Pezzella F. Microvascular density and hypoxia-inducible factor pathway in pancreatic endocrine tumours: negative correlation of microvascular density and VEGF expression with tumour progression. Br J Cancer 2005; 92:94-101. [PMID: 15558070 PMCID: PMC2361752 DOI: 10.1038/sj.bjc.6602245] [Citation(s) in RCA: 179] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Tumour-associated angiogenesis is partly regulated by the hypoxia-inducible factor (HIF) pathway. Endocrine tumours are highly vascularised and the molecular mechanisms of their angiogenesis are not fully delineated. The aim of this study is to evaluate angiogenesis and expression of HIF-related molecules in a series of patients with pancreatic endocrine tumours (PETs). The expression of vascular endothelial growth factor (VEGF), HIF-1alpha, HIF-2alpha and carbonic anhydrase 9 (CA9) was examined by immunohistochemistry in 45 patients with PETs and compared to microvascular density (MVD), endothelial proliferation, tumour stage and survival. Microvascular density was very high in PETs and associated with a low endothelial index of proliferation. Microvascular density was significantly higher in benign PETs than in PETs of uncertain prognosis, well-differentiated and poorly differentiated carcinomas (mean values: 535, 436, 252 and 45 vessels mm(-2), respectively, P < 0.0001). Well-differentiated tumours had high cytoplasmic VEGF and HIF-1alpha expression. Poorly differentiated carcinomas were associated with nuclear HIF-1alpha and membranous CA9 expression. Low MVD (P = 0.0001) and membranous CA9 expression (P = 0.0004) were associated with a poorer survival. Contrary to other types of cancer, PETs are highly vascularised, but poorly angiogenic tumours. As they progress, VEGF expression is lost and MVD significantly decreases. The regulation of HIF signalling appears to be specific in pancreatic endocrine tumours.
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Affiliation(s)
- A Couvelard
- Department of Pathology, Hôpital Beaujon, 100 Boulevard du Général Leclerc, 92110 Clichy, France.
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510
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Kamura T, Maenaka K, Kotoshiba S, Matsumoto M, Kohda D, Conaway RC, Conaway JW, Nakayama KI. VHL-box and SOCS-box domains determine binding specificity for Cul2-Rbx1 and Cul5-Rbx2 modules of ubiquitin ligases. Genes Dev 2005; 18:3055-65. [PMID: 15601820 PMCID: PMC535916 DOI: 10.1101/gad.1252404] [Citation(s) in RCA: 379] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The ECS (Elongin B/C-Cul2/Cul5-SOCS-box protein) complex is a member of a family of ubiquitin ligases that share a Cullin-Rbx module. SOCS-box proteins recruit substrates to the ECS complex and are linked to Cullin-Rbx via Elongin B/C. VHL has been implicated as a SOCS-box protein, but lacks a C-terminal sequence (downstream of the BC box) of the SOCS box. We now show that VHL specifically interacts with endogenous Cul2-Rbx1 in mammalian cells, whereas SOCS-box proteins associate with Cul5-Rbx2. We also identify LRR-1 and FEM1B as proteins that share a region of homology with VHL (the VHL box, including the BC box and downstream residues) and associate with Cul2-Rbx1. ECS complexes can thus be classified into two distinct protein assemblies, that is, those that contain a subunit with a VHL box (composed of the BC box and a downstream Cul2 box) that interacts with Cul2-Rbx1, and those that contain a subunit with a SOCS box (BC box and downstream Cul5 box) that interacts with Cul5-Rbx2. Domain-swapping analyses showed that the specificity of interaction of VHL-box and SOCS-box proteins with Cullin-Rbx modules is determined by the Cul2 and Cul5 boxes, respectively. Finally, RNAi-mediated knockdown of the Cul2-Rbx1 inhibited the VHL-mediated degradation of HIF-2alpha, whereas knockdown of Cul5-Rbx2 did not affect it. These data suggest that the functions of the Cul2-Rbx1 and Cul5-Rbx2 modules are distinct.
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Affiliation(s)
- Takumi Kamura
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, Higashi-ku, Fukuoka, Fukuoka 812-8582, Japan
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511
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Willems AR, Schwab M, Tyers M. A hitchhiker's guide to the cullin ubiquitin ligases: SCF and its kin. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2005; 1695:133-70. [PMID: 15571813 DOI: 10.1016/j.bbamcr.2004.09.027] [Citation(s) in RCA: 371] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The SCF (Skp1-Cullin-F-box) E3 ubiquitin ligase family was discovered through genetic requirements for cell cycle progression in budding yeast. In these multisubunit enzymes, an invariant core complex, composed of the Skp1 linker protein, the Cdc53/Cul1 scaffold protein and the Rbx1/Roc1/Hrt1 RING domain protein, engages one of a suite of substrate adaptors called F-box proteins that in turn recruit substrates for ubiquitination by an associated E2 enzyme. The cullin-RING domain-adaptor architecture has diversified through evolution, such that in total many hundreds of distinct SCF and SCF-like complexes enable degradation of myriad substrates. Substrate recognition by adaptors often depends on posttranslational modification of the substrate, which thus places substrate stability under dynamic regulation by intracellular signaling events. SCF complexes control cell proliferation through degradation of critical regulators such as cyclins, CDK inhibitors and transcription factors. A plethora of other processes in development and disease are controlled by other SCF-like complexes, including those based on Cul2-SOCS-box adaptor protein and Cul3-BTB domain adaptor protein combinations. Recent structural insights into SCF-like complexes have begun to illuminate aspects of substrate recognition and catalytic reaction mechanisms.
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Affiliation(s)
- Andrew R Willems
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, Canada, M5G 1X5
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512
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Petrella BL, Lohi J, Brinckerhoff CE. Identification of membrane type-1 matrix metalloproteinase as a target of hypoxia-inducible factor-2 alpha in von Hippel-Lindau renal cell carcinoma. Oncogene 2005; 24:1043-52. [PMID: 15592504 PMCID: PMC1847637 DOI: 10.1038/sj.onc.1208305] [Citation(s) in RCA: 136] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Metastatic renal cell carcinoma (RCC) resulting from the hereditary loss of the von Hippel-Lindau (VHL) tumor suppressor gene is the leading cause of death in VHL patients due to the deleterious effects of the metastatic tumor(s). VHL functions in the destruction of the alpha subunits of the heterodimeric transcription factor, hypoxia-inducible factor (HIF-1 alpha and HIF-2 alpha), in normoxic conditions. When VHL function is lost, HIF-alpha protein is stabilized, and target hypoxia-inducible genes are transcribed. The process of tumor invasion and metastasis involves the destruction of the extracellular matrix, which is accomplished primarily by the matrix metalloproteinase (MMP) family of enzymes. Here, we describe a connection between the loss of VHL tumor suppressor function and the upregulation of membrane type-1 MMP (MT1-MMP) gene expression and protein. Specifically, MT1-MMP is upregulated in VHL-/- RCC cells through an increase in gene transcription, which is mediated by the cooperative effects of the transcription factors, HIF-2 and Sp1. Further, we identify a functional HIF-binding site in the proximal promoter of MT1-MMP. To our knowledge, this is the first report to show direct regulation of MT1-MMP by HIF-2 and to provide a direct link between the loss of VHL tumor suppressor function and an increase in MMP gene and protein expression.
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Affiliation(s)
- Brenda L. Petrella
- Department of Biochemistry, Dartmouth Medical School, Lebanon, NH 03756, USA
| | - Jouko Lohi
- Department of Pathology, Haartman Institute, University of Helsinki and Helsinki University Central Hospital, Helsinki, FIN-00014, Finland
| | - Constance E. Brinckerhoff
- Department of Biochemistry, Dartmouth Medical School, Lebanon, NH 03756, USA
- Department of Medicine, Norris Cotton Cancer Center, Dartmouth Medical School, Lebanon, NH 03756, USA
- *To whom correspondence should be addressed. Constance E. Brinckerhoff, Ph.D. Norris Cotton Cancer Center, Dartmouth Medical School, Department of Medicine, 1 Medical Center Drive, Rubin Building, HB#7936, Lebanon, NH 03756, Telephone: (603)653-9957, Fax: (603)653-9952,
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513
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Gimm O. Pheochromocytoma-associated syndromes: genes, proteins and functions of RET, VHL and SDHx. Fam Cancer 2005; 4:17-23. [PMID: 15883706 DOI: 10.1007/s10689-004-5740-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2004] [Accepted: 04/01/2004] [Indexed: 10/25/2022]
Abstract
Pheochromocytoma are tumors derived from chromaffin cells that secrete catecholamines. These catecholamines may lead to increased blood pressure and even death. Historically, pheochromocytoma have been described as 10 tumor, i.e. about 10 were believed to be malignant, 10 were found to be extra-adrenal, and 10 were meant to be bilateral. Also, about 10 were considered to be hereditary. In these instances, they were most often part of either the multiple endocrine neoplasia type 2 (MEN 2) syndrome or the von Hippel-Lindau (VHL) disease. The genes (RET and VHL) involved have been known for several years and their function is the subject of ongoing investigation. Very recently, several genes (SDHD, SDHB, and SDHC) that belong to the mitochondrial complex II have been identified to be involved in the so-called pheochromocytoma-paraganglioma syndrome. Only SDHD and SDHB have so far been implicated in the pathogenesis of pheochromocytoma.
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Affiliation(s)
- O Gimm
- Department of General, Visceral and Vascular Surgery, University of Halle, Halle, Germany.
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514
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Opocher G, Conton P, Schiavi F, Macino B, Mantero F. Pheochromocytoma in von Hippel–Lindau disease and neurofibromatosis type 1. Fam Cancer 2005; 4:13-6. [PMID: 15883705 DOI: 10.1007/s10689-004-6128-y] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2004] [Accepted: 11/10/2004] [Indexed: 11/30/2022]
Abstract
Clinical and genetic understanding of chromaffin tumors has been greatly enhanced in the last few years. Although some pheochromocytoma genes may still be unknown, the role of RET, VHL, SDHB, SDHD and NF1 genes is unequivocal and phenotypes are also being better characterized. The loss of function of VHL and NF1 genes can lead to a variety of tumors including phechromocytoma and their mechanism of action is under intensive investigation. Many different mutations are responsible for VHL gene inactivation but only missense mutations have been described so far in families with pheochromocytoma. Because of its large size extensive mutation analysis of the NF1 gene has seldom been performed, and mutations have only been identified in about 15% of patients. Several point mutations have been found in exon 31. Differences in pheochromocytoma phenotype in VHL or NF1 are not very pronounced, but it may be of some interest to consider the two groups separately. In VHL, pheochromocytoma has an earlier onset than in sporadic forms, it is often multiple, and malignancy is less frequent. The mean age of diagnosis is 28 years, the youngest patient being 5 years old. In NF1 patients pheochromocytoma phenotype is similar to sporadic forms. The mean age of pheochromocytoma onset is 42 years; 84% of patients have solitary adrenal tumors, 9.6% have bilateral adrenal disease and 6.1% have ectopic pheochromocytomas; malignant pheochromocytomas were identified in 11.5% of the cases. The group of pheochromocytoma susceptibility genes includes, along with the tumor suppressor genes VHL and NF1, the proto-oncogene RET and the genes encoding succinate dehydrogenase subunit D and succinate dehydrogenase subunit B. Whether there is a common pathway among these different genes is still a matter of debate.
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Affiliation(s)
- Giuseppe Opocher
- Endocrinology Unit, Department of Medical and Surgical Sciences, University of Padova, Via Ospedale 105, 35128 Padova, Italy.
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515
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Brahimi-Horn MC, Pouysségur J. The hypoxia-inducible factor and tumor progression along the angiogenic pathway. ACTA ACUST UNITED AC 2005; 242:157-213. [PMID: 15598469 DOI: 10.1016/s0074-7696(04)42004-x] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The hypoxia-inducible factor (HIF) is a transcription factor that plays a key role in the response of cells to oxygen levels. HIF is a heterodimer of alpha- and beta-subunits where the alpha-subunit is translated constitutively but has a very short half-life under normal oxygen concentrations. Negative regulation of the half-life and activity of the alpha-subunit is dependent on its posttranslational hydroxylation by hydroxylases that are dependent on oxygen for activity. Thus under low oxygen (hypoxic) conditions the hydroxylases are inactive and the alpha-subunit is stable and able to interact with the beta-subunit to bind and induce transcription of target genes. Hypoxic conditions are encountered in development and in disease states such as cancer. Tumors that have outstripped their blood supply become hypoxic and express high levels of HIF. HIF in turn targets genes that induce survival, glycolysis, and angiogenesis, a form of neovascularization, which ensures the tumor with a continued supply of oxygen and nutrients for further growth.
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Affiliation(s)
- M Christiane Brahimi-Horn
- Institute of Signaling, Developmental Biology and Cancer Research, CNRS UMR 6543, Centre A. Lacassagne, 06189 Nice, France
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516
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Lee YS, Vortmeyer AO, Lubensky IA, Vogel TW, Ikejiri B, Ferlicot S, Benoît G, Giraud S, Oldfield EH, Linehan WM, Teh BT, Richard S, Zhuang Z. Coexpression of Erythropoietin and Erythropoietin Receptor in Von Hippel-Lindau Disease–Associated Renal Cysts and Renal Cell Carcinoma. Clin Cancer Res 2005. [DOI: 10.1158/1078-0432.1059.11.3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Von Hippel-Lindau (VHL) disease is characterized by multiple tumors in specific target organs. The tumors at different sites share distinct morphologic and genetic characteristics but their cell of origin is unknown. We show that VHL disease–associated renal clear cell carcinomas (RCC) consistently coexpress erythropoietin (Epo) and Epo receptor (EpoR). In addition, coexpression of Epo and EpoR is detected in many renal cysts, providing further evidence that renal cysts are potential precursors for RCC. In conjunction with VHL gene deficiency, coexpression of Epo and EpoR in renal cysts and tumors may reflect a developmental arrest in immature mesenchymal cells. Such arrest may lead to autocrine stimulation, cell proliferation, and renal tumor development, similar to tumorigenesis of VHL disease–associated hemangioblastomas.
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Affiliation(s)
- Youn-Soo Lee
- 1Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke and
| | | | - Irina A. Lubensky
- 1Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke and
| | - Timothy W.A. Vogel
- 1Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke and
| | - Barbara Ikejiri
- 1Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke and
| | | | - Gérard Benoît
- 4Service d'Urologie, Hôpital de Bicêtre, Le Kremlin-Bicêtre, France
| | - Sophie Giraud
- 5Laboratoire de Génétique Oncologique EPHE-UMR 8125,Villejuif, France
- 7Genetic Laboratory, Hôpital Édouard Herriot, Lyon, France; and
| | - Edward H. Oldfield
- 1Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke and
| | - W. Marston Linehan
- 2Urologic Oncology Branch, National Cancer Institute, NIH, Bethesda, Maryland
| | - Bin T. Teh
- 8Van Andel Research Institute, Grand Rapids, Michigan
| | - Stéphane Richard
- 4Service d'Urologie, Hôpital de Bicêtre, Le Kremlin-Bicêtre, France
- 5Laboratoire de Génétique Oncologique EPHE-UMR 8125,Villejuif, France
- 6Service de Néphrologie, Hôpital Necker, Paris, France
| | - Zhengping Zhuang
- 1Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke and
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517
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Selak MA, Armour SM, MacKenzie ED, Boulahbel H, Watson DG, Mansfield KD, Pan Y, Simon MC, Thompson CB, Gottlieb E. Succinate links TCA cycle dysfunction to oncogenesis by inhibiting HIF-alpha prolyl hydroxylase. Cancer Cell 2005; 7:77-85. [PMID: 15652751 DOI: 10.1016/j.ccr.2004.11.022] [Citation(s) in RCA: 1513] [Impact Index Per Article: 79.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2004] [Revised: 10/27/2004] [Accepted: 11/05/2004] [Indexed: 01/13/2023]
Abstract
Several mitochondrial proteins are tumor suppressors. These include succinate dehydrogenase (SDH) and fumarate hydratase, both enzymes of the tricarboxylic acid (TCA) cycle. However, to date, the mechanisms by which defects in the TCA cycle contribute to tumor formation have not been elucidated. Here we describe a mitochondrion-to-cytosol signaling pathway that links mitochondrial dysfunction to oncogenic events: succinate, which accumulates as a result of SDH inhibition, inhibits HIF-alpha prolyl hydroxylases in the cytosol, leading to stabilization and activation of HIF-1alpha. These results suggest a mechanistic link between SDH mutations and HIF-1alpha induction, providing an explanation for the highly vascular tumors that develop in the absence of VHL mutations.
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Affiliation(s)
- Mary A Selak
- Apoptosis and Tumour Physiology Laboratory, Beatson Institute for Cancer Research, Cancer Research UK Beatson Laboratories, Switchback Road, Glasgow G61 1BD, United Kingdom
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518
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Kaelin WG. The von Hippel-Lindau tumor suppressor protein: roles in cancer and oxygen sensing. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2005; 70:159-66. [PMID: 16869749 DOI: 10.1101/sqb.2005.70.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Biallelic inactivation of the von Hippel-Lindau (VHL) tumor suppressor gene is a common event in hereditary (von Hippel- Lindau disease) and sporadic hemangioblastomas and clear-cell renal carcinomas. Germ-line VHL mutations are also linked to some hereditary pheochromocytoma families. The VHL gene product, pVHL, interacts with a number of cellular proteins and is implicated in the control of angiogenesis, extracellular matrix formation, cell metabolism, and mitogenesis. The best understood function of pVHL relates to its role as the substrate recognition unit of an E3 ligase that targets the heterodimeric transcription factor HIF (hypoxia-inducible factor) for destruction in the presence of oxygen. Down-regulation of HIF appears to be both necessary and sufficient for renal tumor suppression by pVHL, and HIF is strongly suspected of contributing to hemangioblastoma development as well. Recent work suggests that pVHL's role in pheochromocytoma is not related to HIF but rather to the ability of pVHL to regulate neuronal apoptosis, which is mediated by c-Jun, when growth factors such as NGF become limiting. Loss of pVHL leads to up-regulation of JunB, which antagonizes c-Jun and blunts apoptosis.
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Affiliation(s)
- W G Kaelin
- Howard Hughes Medical Institute, Dana-Farber and Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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519
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Kralovics R, Skoda RC. Molecular pathogenesis of Philadelphia chromosome negative myeloproliferative disorders. Blood Rev 2005; 19:1-13. [PMID: 15572213 DOI: 10.1016/j.blre.2004.02.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
We summarize the current knowledge on molecular alterations in myeloproliferative disorders (MPD), in particular altered in vitro responses of progenitor cells, cytokine signaling, gene expression patterns and genetic lesions. Newly characterized markers, such as altered expression of polycythemia rubra vera-1 (PRV-1) and the thrombopoietin receptor (c-MPL) as well as deletions on chromosome 20q (del20q) and loss of heterozygosity on chromosome 9p (9pLOH) provide an opportunity to diagnose and identify subpopulations of MPD patients. Furthermore, we review familial syndromes that share phenotypic features with sporadic MPD. In some of these families, mutations in the genes for thrombopoietin (TPO), c-MPL, EPO-receptor and the von Hippel-Lindau (VHL) gene have been shown to cause the disease. However, in the majority of familial cases the molecular causes remain unknown. Some of these families display clonal hematopoiesis and other features previously only found in sporadic MPD. Elucidating the molecular defect(s) in these pedigrees will likely be relevant for understanding sporadic MPD pathogenesis.
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Affiliation(s)
- Robert Kralovics
- Department of Research, Experimental Hematology, Basel University Hospital, Hebelstrasse 20, 4031 Basel, Switzerland.
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520
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Abstract
Protein degradation is one of the tactics used by the cell for irreversibly inactivating proteins. In eukaryotes, ATP-dependent protein degradation in the cytoplasm and nucleus is carried out by the 26S proteasome. Most proteins are targeted to the 26S proteasome by covalent attachment of a multiubiquitin chain. A key component of the enzyme cascade that results in attachment of the multiubiquitin chain to the target or labile protein is the ubiquitin ligase that controls the specificity of the ubiquitination reaction. Defects in ubiquitin-dependent proteolysis have been shown to result in a variety of human diseases, including cancer, neurodegenerative diseases, and metabolic disorders. The SCF (Skp1-Cullin-F-box-Hrt1) complex is a heteromeric ubiquitin ligase that multiubiquitinates proteins important for signal transduction and cell cycle progression. A technology was developed known as Protac (Proteolysis Targeting Chimeric Molecule) that acts as a bridge, bringing together the SCF ubiquitin ligase with a protein target, resulting in its ubiquitination and degradation. The Protac contains an SCF-binding peptide moiety at one end that is recognized by SCF that is chemically linked to the binding partner or ligand of the target protein. The first demonstration of the efficacy of Protac technology was the successful recruitment, ubiquitination, and degradation of the protein methionine aminopeptidase-2 (MetAP-2) through a covalent interaction between MetAP-2 and Protac. Subsequently, we demonstrated that Protacs could effectively ubiquitinate and degrade cancer-promoting proteins (estrogen and androgen receptors) through noncovalent interactions in vitro and in cells. Finally, cell-permeable Protacs can also promote the degradation of proteins in cells. This chapter includes experiments to test the ability of Protacs to target proteins in vitro and in cells.
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Affiliation(s)
- Kathleen M Sakamoto
- Department of Pediatrics, Division of Hematology- Oncology Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, Los Angeles, California, USA
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521
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Giles RH, Voest EE. Tumor suppressors APC and VHL: gatekeepers of the intestine and kidney. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2005; 40:151-81. [PMID: 17153484 DOI: 10.1007/3-540-27671-8_7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Affiliation(s)
- Rachel H Giles
- Department Medical Oncology, University Medical Center Utrecht, Utrecht, The Netherlands.
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522
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Dirac AMG, Nijman SMB, Brummelkamp TR, Bernards R. Functional annotation of deubiquitinating enzymes using RNA interference. Methods Enzymol 2005; 398:554-67. [PMID: 16275358 DOI: 10.1016/s0076-6879(05)98045-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Protein ubiquitination is a dynamic process, depending on a tightly regulated balance between the activity of ubiquitin ligases and their antagonists, the ubiquitin-specific proteases or deubiquitinating enzymes. The family of ubiquitin ligases has been studied intensively and it is well established that their deregulation contributes to diverse disease processes, including cancer. Much less is known about the function and regulation of the large group of deubiquitinating enzymes. This chapter describes how RNA interference against deubiquitinating enzymes can be used to elucidate their function. The application of this technology will greatly improve the functional annotation of this family of proteases.
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Affiliation(s)
- Annette M G Dirac
- Division of Molecular Carcinogenesis and Center for Biomedical Genetics, The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
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523
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Biju MP, Neumann AK, Bensinger SJ, Johnson RS, Turka LA, Haase VH. Vhlh gene deletion induces Hif-1-mediated cell death in thymocytes. Mol Cell Biol 2004; 24:9038-47. [PMID: 15456877 PMCID: PMC517905 DOI: 10.1128/mcb.24.20.9038-9047.2004] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The von Hippel-Lindau gene product (pVHL) targets the alpha subunit of basic helix-loop-helix transcription factor hypoxia-inducible factor (HIF) for proteasomal degradation. Inactivation of pVhl in the mouse germ line results in embryonic lethality, indicating that tight control of Hif-mediated adaptive responses to hypoxia is required for normal development and tissue function. In order to investigate the role of pVhl in T-cell development, we generated mice with thymocyte-specific inactivation of Vhlh resulting in constitutive transcriptional activity of Hif-1, as well as mice with thymocyte-specific repression of Hif-1 in a wild-type and Vhlh-deficient background. Thymi from Vhlh-deficient mice were small due to a severe reduction in the total number of CD4/CD8-double-positive thymocytes which was associated with increased apoptosis in vivo and in vitro. Increased apoptosis was a result of enhanced caspase 8 activity, while Bcl-2 and Bcl-XL transgene expression had little effect on this phenotype. Inactivation of Hif-1 in Vhlh-deficient thymocytes restored thymic cellularity as well as thymocyte viability in vitro. Our data suggest that tight regulation of Hif-1 via pVhl is required for normal thymocyte development and viability and that an increase in Hif-1 transcriptional activity enhances caspase 8-mediated apoptosis in thymocytes.
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Affiliation(s)
- Mangatt P Biju
- Department of Medicine, 700 Clinical Research Building, 415 Curie Blvd., Philadelphia, PA 19104-6144, USA
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524
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Abstract
Disruption of the normal regulation of cell-cycle progression and division lies at the heart of the events leading to cancer. Complex networks of regulatory factors, the tumour microenvironment and stress signals, such as those resulting from damaged DNA, dictate whether cancer cells proliferate or die. Recent progress in understanding the molecular changes that underlie cancer development offer the prospect of specifically targeting malfunctioning molecules and pathways to achieve more effective and rational cancer therapy.
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Affiliation(s)
- Charles Sawyers
- Howard Hughes Medical Institute, David Geffen School of Medicine at UCLA, Jonsson Comprehensive Cancer Center, 10833 LeConte Avenue, Los Angeles, California 90095, USA.
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525
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Perry E, Tsruya R, Levitsky P, Pomp O, Taller M, Weisberg S, Parris W, Kulkarni S, Malovani H, Pawson T, Shpungin S, Nir U. TMF/ARA160 is a BC-box-containing protein that mediates the degradation of Stat3. Oncogene 2004; 23:8908-19. [PMID: 15467733 DOI: 10.1038/sj.onc.1208149] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
TMF/ARA160 is a Golgi resident protein whose cellular functions have not been conclusively revealed. Herein we show that TMF/ARA160 can direct the proteasomal degradation of the key cell growth regulator - Stat3. TMF/ARA160 was dispersed in the cytoplasm of myogenic C2C12 cells that were grown under low-serum conditions. The cytoplasmic distribution of TMF/ARA160 was accompanied by its transient association with the tyrosine kinase Fer and with Stat3, which underwent proteasomal degradation under those conditions. Moreover, serum deprivation induced the association of ubiquitinated proteins, with the TMF/ARA160 complex. However, TMF/ARA160 did not bind Stat1, whose cellular levels were increased in serum-starved C2C12 cells. Amino-acid sequence analysis identified a BC-box element in TMF/ARA160 that mediated the binding of this protein to elongin C. Ectopic expression of TMF/ARA160 in serum-starved C2C12 cells drove the ubiquitination and proteasomal degradation of Stat3, an effect that was not caused by TMF/ARA160 devoid of the BC-box motif. Thus, the Golgi apparatus harbors a novel BC-box-containing protein that can direct Stat3 to proteasomal degradation. Interestingly, the level of TMF/ARA160 was significantly decreased in malignant brain tumors, implying a suppressive role of that protein in tumor progression.
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Affiliation(s)
- Erez Perry
- Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 52900, Israel
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526
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Abstract
Current standard treatments for patients with metastatic (stage IV) renal cell carcinoma involve both surgical removal of tumors and treatment with biological agents such as interleukin 2 and/or IFN-alpha. Unfortunately, such approaches are inadequate for most patients with stage IV disease; the result is a median time to progression of 2 to 4 months and an overall survival of 6 to 17 months. Standard chemotherapy has been uniformly disappointing in this disorder. It is clear that new therapies are needed to approach these patients. Recently, a greater understanding of cancer genetics has led to the successful development of novel therapeutics directed against targets linked to specific types of cancer. During the past decade, researchers have identified the von Hippel-Lindau (VHL) gene as an important tumor suppressor in clear cell carcinoma of the kidney. Elucidation of the VHL gene product (pVHL) and its regulation of hypoxia-inducible factor signaling have created a potential genetic basis for growth factor-targeted strategies in this disease. This review will focus on the potential growth factor targets in clear cell carcinoma, their relation to VHL and hypoxia-inducible factor, and the clinical challenges that face their development.
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Affiliation(s)
- Anil Potti
- Division of Hematology, Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA
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527
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Olenyuk BZ, Zhang GJ, Klco JM, Nickols NG, Kaelin WG, Dervan PB. Inhibition of vascular endothelial growth factor with a sequence-specific hypoxia response element antagonist. Proc Natl Acad Sci U S A 2004; 101:16768-73. [PMID: 15556999 PMCID: PMC534742 DOI: 10.1073/pnas.0407617101] [Citation(s) in RCA: 184] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Vascular endothelial growth factor (VEGF) and its receptors have been implicated as key factors in tumor angiogenesis that are up-regulated by hypoxia. We evaluated the effects of DNA-binding small molecules on hypoxia-inducible transcription of VEGF. A synthetic pyrrole-imidazole polyamide designed to bind the hypoxia response element (HRE) was found to disrupt hypoxia-inducible factor (HIF) binding to HRE. In cultured HeLa cells, this resulted in a reduction of VEGF mRNA and secreted protein levels. The observed effects were polyamide-specific and dose-dependent. Analysis of genome-wide effects of the HRE-specific polyamide revealed that a number of hypoxia-inducible genes were down-regulated. Pathway-based regulation of hypoxia-inducible gene expression with DNA-binding small molecules may represent a new approach for targeting angiogenesis.
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Affiliation(s)
- Bogdan Z Olenyuk
- Division of Chemistry and Chemical Engineering, Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA
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528
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Brugarolas J, Lei K, Hurley RL, Manning BD, Reiling JH, Hafen E, Witters LA, Ellisen LW, Kaelin WG. Regulation of mTOR function in response to hypoxia by REDD1 and the TSC1/TSC2 tumor suppressor complex. Genes Dev 2004; 18:2893-904. [PMID: 15545625 PMCID: PMC534650 DOI: 10.1101/gad.1256804] [Citation(s) in RCA: 1025] [Impact Index Per Article: 51.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Mammalian target of rapamycin (mTOR) is a central regulator of protein synthesis whose activity is modulated by a variety of signals. Energy depletion and hypoxia result in mTOR inhibition. While energy depletion inhibits mTOR through a process involving the activation of AMP-activated protein kinase (AMPK) by LKB1 and subsequent phosphorylation of TSC2, the mechanism of mTOR inhibition by hypoxia is not known. Here we show that mTOR inhibition by hypoxia requires the TSC1/TSC2 tumor suppressor complex and the hypoxia-inducible gene REDD1/RTP801. Disruption of the TSC1/TSC2 complex through loss of TSC1 or TSC2 blocks the effects of hypoxia on mTOR, as measured by changes in the mTOR targets S6K and 4E-BP1, and results in abnormal accumulation of Hypoxia-inducible factor (HIF). In contrast to energy depletion, mTOR inhibition by hypoxia does not require AMPK or LKB1. Down-regulation of mTOR activity by hypoxia requires de novo mRNA synthesis and correlates with increased expression of the hypoxia-inducible REDD1 gene. Disruption of REDD1 abrogates the hypoxia-induced inhibition of mTOR, and REDD1 overexpression is sufficient to down-regulate S6K phosphorylation in a TSC1/TSC2-dependent manner. Inhibition of mTOR function by hypoxia is likely to be important for tumor suppression as TSC2-deficient cells maintain abnormally high levels of cell proliferation under hypoxia.
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Affiliation(s)
- James Brugarolas
- Dana-Farber Cancer Institute and Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
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529
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Richard S, Lidereau R, Giraud S. The growing family of hereditary renal cell carcinoma. Nephrol Dial Transplant 2004; 19:2954-8. [PMID: 15507478 DOI: 10.1093/ndt/gfh535] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Affiliation(s)
- Stéphane Richard
- Génétique Oncologique EPHE, Faculté de Médecine Paris-Sud, 94276 Le Kremlin-Bicêtre, France.
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530
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Mazure NM, Brahimi-Horn MC, Berta MA, Benizri E, Bilton RL, Dayan F, Ginouvès A, Berra E, Pouysségur J. HIF-1: master and commander of the hypoxic world. A pharmacological approach to its regulation by siRNAs. Biochem Pharmacol 2004; 68:971-80. [PMID: 15313390 DOI: 10.1016/j.bcp.2004.04.022] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2004] [Accepted: 04/21/2004] [Indexed: 11/23/2022]
Abstract
The hypoxia-inducible factor-1 (HIF-1) is primarily involved in the sensing and adapting of cells to changes in the O2 level, which is essential for their viability. It is important that this critical transcription factor be tightly regulated in order for cells to respond to a wide range of O2 concentrations. HIF-1 regulation by post-translational modification is the central theme of the scenario of O2 homeostasis. The alpha subunit of HIF-1 is the principal actor while the supporting actors (PHDs, FIH-1, ARD1, CITED2, p300...) all contribute to the complexity of the grand finale. It is well established that HIF-1 expression and activation correlates with tumor progression and resistance to cancer treatments. We will introduce the different actors involved in HIF-1 regulation, and their mechanisms of action via invalidation by siRNAs and discuss therapies targeting HIF-1, to selectively kill tumor cells that adapt to low O2 concentrations.
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Affiliation(s)
- Nathalie M Mazure
- Institute of Signaling, Developmental Biology and Cancer Research, CNRS-UMR 6543, Centre Antoine Lacassagne, 33 Avenue de Valombrose, 06189 Nice, France
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531
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Kobayashi A, Kang MI, Okawa H, Ohtsuji M, Zenke Y, Chiba T, Igarashi K, Yamamoto M. Oxidative stress sensor Keap1 functions as an adaptor for Cul3-based E3 ligase to regulate proteasomal degradation of Nrf2. Mol Cell Biol 2004; 24:7130-9. [PMID: 15282312 PMCID: PMC479737 DOI: 10.1128/mcb.24.16.7130-7139.2004] [Citation(s) in RCA: 1706] [Impact Index Per Article: 85.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Transcription factor Nrf2 is a major regulator of genes encoding phase 2 detoxifying enzymes and antioxidant stress proteins in response to electrophilic agents and oxidative stress. In the absence of such stimuli, Nrf2 is inactive owing to its cytoplasmic retention by Keap1 and rapid degradation through the proteasome system. We examined the contribution of Keap1 to the rapid turnover of Nrf2 (half-life of less than 20 min) and found that a direct association between Keap1 and Nrf2 is required for Nrf2 degradation. In a series of domain function analyses of Keap1, we found that both the BTB and intervening-region (IVR) domains are crucial for Nrf2 degradation, implying that these two domains act to recruit ubiquitin-proteasome factors. Indeed, Cullin 3 (Cul3), a subunit of the E3 ligase complex, was found to interact specifically with Keap1 in vivo. Keap1 associates with the N-terminal region of Cul3 through the IVR domain and promotes the ubiquitination of Nrf2 in cooperation with the Cul3-Roc1 complex. These results thus provide solid evidence that Keap1 functions as an adaptor of Cul3-based E3 ligase. To our knowledge, Nrf2 and Keap1 are the first reported mammalian substrate and adaptor, respectively, of the Cul3-based E3 ligase system.
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Affiliation(s)
- Akira Kobayashi
- Center for Tsukuba Advanced Research Alliance, Institute of Basic Medical Sciences, and JST-ERATO Environmental Response Project, University of Tsukuba, Tsukuba 305-8575, Japan
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532
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Bishop T, Lau KW, Epstein ACR, Kim SK, Jiang M, O'Rourke D, Pugh CW, Gleadle JM, Taylor MS, Hodgkin J, Ratcliffe PJ. Genetic analysis of pathways regulated by the von Hippel-Lindau tumor suppressor in Caenorhabditis elegans. PLoS Biol 2004; 2:e289. [PMID: 15361934 PMCID: PMC515368 DOI: 10.1371/journal.pbio.0020289] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2004] [Accepted: 06/29/2004] [Indexed: 11/19/2022] Open
Abstract
The von Hippel-Lindau (VHL) tumor suppressor functions as a ubiquitin ligase that mediates proteolytic inactivation of hydroxylated α subunits of hypoxia-inducible factor (HIF). Although studies of VHL-defective renal carcinoma cells suggest the existence of other VHL tumor suppressor pathways, dysregulation of the HIF transcriptional cascade has extensive effects that make it difficult to distinguish whether, and to what extent, observed abnormalities in these cells represent effects on pathways that are distinct from HIF. Here, we report on a genetic analysis of HIF-dependent and -independent effects of VHL inactivation by studying gene expression patterns in Caenorhabditis elegans. We show tight conservation of the HIF-1/VHL-1/EGL-9 hydroxylase pathway. However, persisting differential gene expression in hif-1 versus hif-1; vhl-1 double mutant worms clearly distinguished HIF-1–independent effects of VHL-1 inactivation. Genomic clustering, predicted functional similarities, and a common pattern of dysregulation in both vhl-1 worms and a set of mutants (dpy-18, let-268, gon-1, mig-17, and unc-6), with different defects in extracellular matrix formation, suggest that dysregulation of these genes reflects a discrete HIF-1–independent function of VHL-1 that is connected with extracellular matrix function. Besides its known function of inactivating hypoxia-inducible factor (HIF), genetically engineered worms clearly demonstrate that there exist HIF-independent effects of the von Hippel- Lindau tumor suppressor
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Affiliation(s)
- Tammie Bishop
- 1The Henry Wellcome Building of Genomic Medicine, University of OxfordOxfordUnited Kingdom
| | - Kah Weng Lau
- 1The Henry Wellcome Building of Genomic Medicine, University of OxfordOxfordUnited Kingdom
| | - Andrew C. R Epstein
- 1The Henry Wellcome Building of Genomic Medicine, University of OxfordOxfordUnited Kingdom
| | - Stuart K Kim
- 2Department of Developmental Biology and Genetics, Stanford University Medical CenterStanford, CaliforniaUnited States of America
| | - Min Jiang
- 2Department of Developmental Biology and Genetics, Stanford University Medical CenterStanford, CaliforniaUnited States of America
| | - Delia O'Rourke
- 3Department of Biochemistry, University of OxfordOxfordUnited Kingdom
| | - Christopher W Pugh
- 1The Henry Wellcome Building of Genomic Medicine, University of OxfordOxfordUnited Kingdom
| | - Jonathan M Gleadle
- 1The Henry Wellcome Building of Genomic Medicine, University of OxfordOxfordUnited Kingdom
| | - Martin S Taylor
- 1The Henry Wellcome Building of Genomic Medicine, University of OxfordOxfordUnited Kingdom
| | - Jonathan Hodgkin
- 3Department of Biochemistry, University of OxfordOxfordUnited Kingdom
| | - Peter J Ratcliffe
- 1The Henry Wellcome Building of Genomic Medicine, University of OxfordOxfordUnited Kingdom
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533
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Barry RE, Krek W. The von Hippel–Lindau tumour suppressor: a multi-faceted inhibitor of tumourigenesis. Trends Mol Med 2004; 10:466-72. [PMID: 15350900 DOI: 10.1016/j.molmed.2004.07.008] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Robert E Barry
- Institute of Cell Biology, ETH Hönggerberg, CH-8093 Zurich, Switzerland
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534
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Affiliation(s)
- W Marston Linehan
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA.
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535
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Gallou C, Chauveau D, Richard S, Joly D, Giraud S, Olschwang S, Martin N, Saquet C, Chrétien Y, Méjean A, Correas JM, Benoît G, Colombeau P, Grünfeld JP, Junien C, Béroud C. Genotype-phenotype correlation in von Hippel-Lindau families with renal lesions. Hum Mutat 2004; 24:215-24. [PMID: 15300849 DOI: 10.1002/humu.20082] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
von Hippel-Lindau (VHL) disease arises from mutations in the VHL gene and predisposes patients to develop a variety of tumors in different organs. In the kidney, single or multiple cysts and renal cell carcinomas (RCC) may occur. Both inter- and intrafamilial heterogeneity in clinical expression are well recognized. To identify VHL-dependent genetic factors, we investigated the renal phenotype in 274 individuals from 126 unrelated VHL families in whom 92 different VHL mutations were characterized. The incidence of renal involvement was increased in families with mutations leading to truncated protein (MLTP) or large rearrangement, as compared to families with missense changes (81 vs. 63%, respectively; P=0.03). In the latter group, we identified two mutation cluster regions (MCRs) associated with a high risk of harboring renal lesions: MCR-1 (codons 74-90) and MCR-2 (codons 130-136). In addition, the incidence of RCC was higher in families with MLTP than in families with missense changes (75 vs. 57%; P=0.04). Furthermore, mutations within MCR-1 but not MCR-2 conferred genetic susceptibility to develop RCC. Overall, our data argued for a substantial contribution of the genetic change in the VHL gene to susceptibility to renal phenotype in VHL patients.
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MESH Headings
- Adult
- Amino Acid Substitution
- Carcinoma, Renal Cell/epidemiology
- Carcinoma, Renal Cell/genetics
- Carcinoma, Renal Cell/pathology
- Codon
- Codon, Nonsense
- Codon, Terminator
- Exons/genetics
- Female
- France/epidemiology
- Genotype
- Humans
- Incidence
- Kidney Diseases, Cystic/epidemiology
- Kidney Diseases, Cystic/genetics
- Kidney Diseases, Cystic/pathology
- Kidney Neoplasms/epidemiology
- Kidney Neoplasms/genetics
- Kidney Neoplasms/pathology
- Male
- Middle Aged
- Mutation, Missense
- Phenotype
- Polymerase Chain Reaction
- Polymorphism, Single-Stranded Conformational
- Protein Structure, Tertiary
- Risk
- Sequence Deletion
- Tumor Suppressor Proteins/chemistry
- Tumor Suppressor Proteins/genetics
- Ubiquitin-Protein Ligases/chemistry
- Ubiquitin-Protein Ligases/genetics
- Von Hippel-Lindau Tumor Suppressor Protein
- von Hippel-Lindau Disease/genetics
- von Hippel-Lindau Disease/pathology
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536
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Affiliation(s)
- Hitoshi Okada
- Institute for Breast Cancer Research/Ontario Cancer Institute, 620 University Avenue, Toronto, Ontario, Canada M5G 2C1
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537
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Griffin ME, Hamilton BJ, Roy KM, Du M, Willson AM, Keenan BJ, Wang XW, Nichols RC. Post-transcriptional regulation of glucose transporter-1 by an AU-rich element in the 3'UTR and by hnRNP A2. Biochem Biophys Res Commun 2004; 318:977-82. [PMID: 15147968 DOI: 10.1016/j.bbrc.2004.04.128] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2004] [Indexed: 11/20/2022]
Abstract
Glucose transporter-1 (GLUT1) mediates uptake of glucose and is up-regulated in some cancers. The amount of this membrane protein is regulated by a post-transcriptional mechanism in which mRNA binding proteins recognize cis-acting elements in the 3'-untranslated (3'UTR) of the mRNA. To identify cis elements in GLUT1 mRNA we introduced 3'UTR sequences into the 3'UTR of the luciferase gene in a reporter construct. A 30 nt adenosine-uridine-rich element ("GLUT1 AURE") inhibited luciferase activity in HEK-293 cells. This inhibitory effect was confirmed by deleting the GLUT1 AURE from a reporter containing the full-length 3'UTR. Deletion of the GLUT1 AURE caused reporter activity to increase. Deletion of a larger fragment ("Bsu" region) containing the GLUT1 AURE increased reporter activity still further, suggesting that there are additional cis elements in the GLUT1 mRNA. The GLUT1 AURE was also active in GBM-T98G glioblastoma cells. Next, we tested the action of a trans-acting factor, hnRNP A2, on GLUT1 gene expression. We show that a cytoplasmic-localizing isoform of hnRNP A2 binds human GLUT1 RNA by gel-shift assay and by UV-crosslinking. Finally, over-expression of the hnRNP A2 isoform inhibited GLUT1 reporter expression in GBM-T98G cells. These results identify the AURE cis element in human GLUT1 mRNA and show that hnRNP A2 acts on GLUT1 mRNA to inhibit expression of GLUT1 in a brain cancer cell line.
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Affiliation(s)
- Mary E Griffin
- Veterans Administration Research Service, White River Junction, VT 05009-0001, USA
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538
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Appelhoff RJ, Tian YM, Raval RR, Turley H, Harris AL, Pugh CW, Ratcliffe PJ, Gleadle JM. Differential function of the prolyl hydroxylases PHD1, PHD2, and PHD3 in the regulation of hypoxia-inducible factor. J Biol Chem 2004; 279:38458-65. [PMID: 15247232 DOI: 10.1074/jbc.m406026200] [Citation(s) in RCA: 810] [Impact Index Per Article: 40.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Hypoxia-inducible factor (HIF) is a transcriptional regulator that plays a key role in many aspects of oxygen homeostasis. The heterodimeric HIF complex is regulated by proteolysis of its alpha-subunits, following oxygen-dependent hydroxylation of specific prolyl residues. Although three HIF prolyl hydroxylases, PHD1, PHD2, and PHD3, have been identified that have the potential to catalyze this reaction, the contribution of each isoform to the physiological regulation of HIF remains uncertain. Here we show using suppression by small interference RNA that each of the three PHD isoforms contributes in a non-redundant manner to the regulation of both HIF-1alpha and HIF-2alpha subunits and that the contribution of each PHD under particular culture conditions is strongly dependent on the abundance of the enzyme. Thus in different cell types, isoform-specific patterns of PHD induction by hypoxia and estrogen alter both the relative abundance of the PHDs and their relative contribution to the regulation of HIF. In addition, the PHDs manifest specificity for different prolyl hydroxylation sites within each HIF-alpha subunit, and a degree of selectively between HIF-1alpha and HIF-2alpha isoforms, indicating that differential PHD inhibition has the potential to selectively alter the characteristics of HIF activation.
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Affiliation(s)
- Rebecca J Appelhoff
- Henry Wellcome Bldg. of Genomic Medicine, Roosevelt Drive, Headington, Oxford, UK
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539
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Shiao YH, Forsti A, Egevad L, Anderson LM, Lindblad P, Hemminki K. VHL down-regulation and differential localization as mechanisms in tumorigenesis. Kidney Int 2004; 64:1671-4. [PMID: 14531799 DOI: 10.1046/j.1523-1755.2003.00257.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND The von Hippel-Lindau (VHL) gene has been widely analyzed in many tumors. Early studies in animal tumors suggest that changes in VHL protein level and localization may be also important in tumorigenesis. In this study, we determined the role of VHL protein in human renal cell carcinomas. METHODS Seventy-five human renal cell carcinomas, predominantly of clear cell type (60 of 75), were examined for VHL protein by immunohistochemistry. The level and pattern of protein expression were then compared to VHL mutations and tumor characteristics. RESULTS An apparent decline of VHL level (positive in <50% of tumor cells) was observed in 49 (65%) tumors, a change more frequent than VHL mutations (28 of 75) (37%). In tumors, VHL was localized to the cytoplasm and/or the cell membrane. The occurrence of a predominantly membranous signal was significantly associated with missense mutations (9 of 14 tumors with missense mutations versus 14 of 61 tumors with no or nonmissense mutations, P = 0.0025) and tumor stage (23 of 60 tumors with stage TI versus 0 of 15 tumors with TII and TIII, P = 0.0034). CONCLUSION This study provides the first evidence of the role of VHL protein level and intracellular localization in tumorigenesis in humans.
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Affiliation(s)
- Yih-Horng Shiao
- Laboratory of Comparative Carcinogenesis, National Cancer Institute-Frederick, National Institutes of Health, Frederick, Maryland 21702, USA.
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540
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Mekhail K, Gunaratnam L, Bonicalzi ME, Lee S. HIF activation by pH-dependent nucleolar sequestration of VHL. Nat Cell Biol 2004; 6:642-7. [PMID: 15181450 DOI: 10.1038/ncb1144] [Citation(s) in RCA: 195] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2004] [Accepted: 05/17/2004] [Indexed: 11/08/2022]
Abstract
Hypoxia and acidosis occur in a wide variety of physiological and pathological settings that include muscle stress, tumour development and ischaemic disorders. A central element in the adaptive response to cellular hypoxia is HIF (hypoxia-inducible factor), a transcription factor that activates an array of genes implicated in oxygen homeostasis, tumour vascularization and ischaemic preconditioning. HIF is activated by hypoxia, but undergoes degradation by the VHL (von Hippel-Lindau) tumour suppressor protein in the presence of oxygen. Here, we demonstrate that hypoxia induction or normoxic acidosis can neutralize the function of VHL by triggering its nucleolar sequestration, a regulatory mechanism of protein function that is observed rarely. VHL is confined to nucleoli until neutral pH conditions are reinstated. Nucleolar sequestration of VHL enables HIF to evade destruction in the presence of oxygen and activate its target genes. Our findings suggest that an increase in hydrogen ions elicits a transient and reversible loss of VHL function by promoting its nucleolar sequestration.
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Affiliation(s)
- Karim Mekhail
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, K1H 8M5, Canada
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541
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Yang H, Ivan M, Min JH, Kim WY, Kaelin WG. Analysis of von Hippel-Lindau hereditary cancer syndrome: implications of oxygen sensing. Methods Enzymol 2004; 381:320-35. [PMID: 15063684 DOI: 10.1016/s0076-6879(04)81022-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Affiliation(s)
- Haifeng Yang
- Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
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542
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Affiliation(s)
- Christian P Pavlovich
- Johns Hopkins Bayview Medical Center, Brady Urological Institute, A-345, 4940 Eastern Ave., Baltimore, Maryland 21224, USA.
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543
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Jensen RL, Gillespie D, House P, Layfield L, Shelton C. Endolymphatic sac tumors in patients with and without von Hippel-Lindau disease: the role of genetic mutation, von Hippel-Lindau protein, and hypoxia inducible factor-1alpha expression. J Neurosurg 2004; 100:488-97. [PMID: 15035285 DOI: 10.3171/jns.2004.100.3.0488] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECT Endolymphatic sac (ELS) tumors are low-grade malignancies of the temporal bone that are associated with von Hippel-Lindau (VHL) disease but can also occur sporadically. The VHL gene product VHL protein is important in the regulation of hypoxia inducible factor (HIF)-1alpha, which controls expression of molecules that are important in angiogenesis and cell metabolism. In this study the authors examine the role of VHL and HIF-1 in ELS tumors. METHODS The ELS tumors from three patients were examined using the following method: DNA from tumor tissue was isolated, amplified by polymerase chain reaction and the VHL gene sequence was compared with the known wild-type sequence. Loss of heterozygosity (LOH) studies were performed to confirm the sequencing data. Immunohistochemical evaluation for VHL, HIF-1alpha, vascular endothelial growth factor (VEGF), and carbonic anhydrase IX (CA IX) was performed. Snap-frozen tumor tissue was examined using Western blot and HIF-1 immunoassays for HIF-1alpha and VHL expression. Two patients had sporadic ELS tumors and the other one suffered from VHL disease. Results of VHL gene sequencing were normal in the tissue derived from the sporadic ELS tumors. The ELS tumor, pheochromocytoma, and spinal hemangioblastoma were heterozygous for the same C-to-A transversion found in the germline carried by the patient with VHL disease. No LOH was detected in the tumor tissue obtained in the patient with VHL disease. Expression of HIF-1alpha, VEGF, and CA IX evaluated using immunohistochemical studies was elevated in the VHL-associated tumors. Nevertheless, Western blots and immunoassays for HIF-1alpha did not show elevated expression in these tumors. CONCLUSIONS The sporadic and VHL disease-associated ELS tumors in this study had normal VHL-mediated HIF-1 regulation. This is a result of normal VHL gene expression in the case of the sporadic ELS tumor. In the VHL-associated ELS tumor, this is due to one normal copy of the VHL gene and adequate VHL gene expression.
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Affiliation(s)
- Randy L Jensen
- Department of Neurosurgery, University of Utah, Salt Lake City, Utah 84132-2303, USA.
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544
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Höpfl G, Ogunshola O, Gassmann M. HIFs and tumors--causes and consequences. Am J Physiol Regul Integr Comp Physiol 2004; 286:R608-23. [PMID: 15003941 DOI: 10.1152/ajpregu.00538.2003] [Citation(s) in RCA: 145] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
For most organisms oxygen is essential fo life. When oxygen levels drop below those required to maintain the minimum physiological oxygen requirement of an organism or tissue it is termed hypoxia. To counter act possible deleterious effects of such a state, an immediate molecular response is initiated causing adaptation responses aimed at cell survival. This response is mediated by the hypoxia-inducible factor-1 (HIF-1), which is a heterodimer consisting of an alpha- and a beta-subunit. HIF-1 alpha protein is stabilized under hypoxic conditions and therefore confers selectivity to this response. Hypoxia is characteristic of tumors, mainly because of impaired blood supply resulting from abnormal growth. Over the past few years enormous progress has been made in the attempt to understand how the activation of the physiological response to hypoxia influences neoplastic growth. In this review some aspects of HIF-1 pathway activation in tumors and the consequences for pathophysiology and treatment of neoplasia are discussed.
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Affiliation(s)
- Gisele Höpfl
- Institute of Veterinary Physiology, University of Zürich, Winterthurerstrasse 260, CH-8057 Zürich, Switzerland
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545
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Abstract
Accumulating evidence points to a key role of the ubiquitin-proteasome pathway in oncogenesis. Aberrant proteolysis of substrates involved in cellular processes such as the cell division cycle, gene transcription, the DNA damage response and apoptosis has been reported to contribute significantly to neoplastic transformation. Cullin-dependent ubiquitin ligases (CDLs) form a class of structurally related multisubunit enzymes central to the ubiquitin-mediated proteolysis of many important biological substrates. In this review, we describe the role of CDLs in the ubiquitinylation of cancer-related substrates and discuss how altered ubiquitinylation by CDLs may contribute to tumor development.
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Affiliation(s)
- Daniele Guardavaccaro
- Department of Pathology and NYU Cancer Institute, MSB 599, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA
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546
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Affiliation(s)
- Stéphane Richard
- Génétique Oncologique EPHE, UPRES 1602 and Service d'Urologie, CHU, Le Kremlin-Bicêtre, and Service de Néphrologie, Hôpital Necker, Paris, France.
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547
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Temes E, Martín-Puig S, Aragonés J, Jones DR, Olmos G, Mérida I, Landázuri MO. Role of diacylglycerol induced by hypoxia in the regulation of HIF-1alpha activity. Biochem Biophys Res Commun 2004; 315:44-50. [PMID: 15013423 DOI: 10.1016/j.bbrc.2004.01.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2003] [Indexed: 11/18/2022]
Abstract
Hypoxia-inducible factor 1 (HIF-1) is a critical transcription factor for the adaptation to lowered oxygen environments. We have previously reported that hypoxia induced phosphatidic acid (PA) accumulation through diacylglycerol kinase (DGK) activity and provided evidence that this PA production regulated HIF-1 expression. Here we report that hypoxia also produces a marked intracellular accumulation of diacylglycerol (DAG) in different cell types. The previously proposed inhibitor of phosphatidylcholine phospholipase C (PC-PLC)/sphingomyelin synthase (SMS) activities, D609, specifically abrogates both hypoxia-dependent DAG accumulation and hypoxia-induced HIF-1 expression. We show that DAG-dependent protein kinase C (PKC) isoforms do not play an essential role in the regulation of HIF-1 expression. D609 inhibits PA accumulation triggered by hypoxia, suggesting that DAG could act as substrate for its conversion into PA by DGK upon these conditions. Therefore, this work provides novel evidence for the existence of DAG/PA-dependent intracellular mechanisms involved in the regulation of HIF-1 expression.
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Affiliation(s)
- Elisa Temes
- Servicio de Inmunología, Hospital de la Princesa, Universidad Autónoma de Madrid (UAM), c/Diego de León 62, 28006 Madrid, Spain
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548
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Masson N, Ratcliffe PJ. Analysis of von Hippel-Lindau tumor suppressor as a mediator of cellular oxygen sensing. Methods Enzymol 2004; 381:305-20. [PMID: 15063683 DOI: 10.1016/s0076-6879(04)81021-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Affiliation(s)
- Norma Masson
- The Henry Wellcome Building of Genomic Medicine, University of Oxford, United Kingdom
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549
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Abstract
Loss of von Hippel-Lindau (VHL) protein function results in an autosomal-dominant cancer syndrome known as VHL disease, which manifests as angiomas of the retina, hemangioblastomas of the central nervous system, renal clear-cell carcinomas and pheochromocytomas. VHL tumor suppressor is a specific substrate-recognition component of the E3 ubiquitin complex, which regulates proteasomal degradation of the subunit of the hypoxia inducible transcription factor (HIF). Impaired VHL complex function leads to accumulation of HIF, overexpression of various HIF-induced gene products and formation of highly vascular neoplasia. However, the ubiquitylating role of the VHL complex extends beyond its function in regulating HIF, as it appears to regulate the stability of other proteins that might be involved in various steps of oncogenic processes.
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Affiliation(s)
- Maria F Czyzyk-Krzeska
- Department of Genome Science, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0505, USA.
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550
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Bluyssen HAR, Lolkema MPJK, van Beest M, Boone M, Snijckers CMJT, Los M, Gebbink MFBG, Braam B, Holstege FCP, Giles RH, Voest EE. Fibronectin is a hypoxia-independent target of the tumor suppressor VHL. FEBS Lett 2004; 556:137-42. [PMID: 14706840 DOI: 10.1016/s0014-5793(03)01392-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The von Hippel-Lindau (VHL) tumor suppressor gene regulates the extracellular matrix by controlling fibronectin deposition. To identify novel VHL target genes, we subjected mRNA from VHL-deficient RCC cells (786-0-pRC) and a transfectant re-expressing wildtype VHL (786-0-VHL) to differential expression profiling. Among the differentially expressed genes, we detected that fibronectin is upregulated in the presence of VHL, while it is not affected by hypoxia. Thus regulation of fibronectin deposition by VHL occurs at the transcriptional level, irrespective of oxygen levels.
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Affiliation(s)
- Hans A R Bluyssen
- Department of Medical Oncology, University Medical Center Utrecht, P.O. Box 85500, 3500 GA, Utrecht, The Netherlands
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