From transcriptional profiling to tumor biology in pheochromocytoma and paraganglioma.
ABSTRACT This review summarizes the way in which inherited mutations define global gene expression in pheochromocytoma (PCC) and paraganglioma (PGL), and how the use of gene expression analysis has advanced our understanding of these diseases. The biology of PCC and PGL tumors is diverse and it has become clear that there is no apparent single biology that defines these tumors. However, over the last 20 years, our understanding of the biology of PGL and PCC has been considerably advanced by the discovery of inherited mutations that predispose individuals to developing the disease. More recently, the use of transcriptomics to stratify tumors based on their gene expression profiles has, in particular, played a vital role in delineating novel mutations involved in the pathogenesis of these tumors. In this review, we describe our current understanding of the biology of cluster 1 (pseudohypoxic) tumors and how mutations that result in the pseudohypoxic phenotype that leads to changes in global gene expression. We also review the advances in our understanding of cluster 2 tumors, and in particular, focus on the newly described MAX tumors.
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ABSTRACT: Warburg's metabolic hypothesis is based on the assumption that a cancer cell's respiration must be under attack, leading to its damage, in order to obtain increased glycolysis. Although this may not apply to all cancers, there is some evidence proving that primarily abnormally functioning mitochondrial complexes are indeed related to cancer development. Thus, mutations in complex II (succinate dehydrogenase (SDH)) lead to the formation of pheochromocytoma/paraganglioma. Mutations in one of the SDH genes (SDHx mutations) lead to succinate accumulation associated with very low fumarate levels, increased glutaminolysis, the generation of reactive oxygen species (ROS), and pseudohypoxia. This results in significant changes in signaling pathways (many of them dependent on the stabilization of hypoxia-inducible factor (HIF)) including oxidative phosphorylation, glycolysis, specific expression profiles, as well as genomic instability and increased mutability resulting in tumor development. Although there is currently no very effective therapy for SDHx-related metastatic pheochromocytomas/paragangliomas, targeting their fundamental metabolic abnormalities may provide a unique opportunity for the development of novel and more effective forms of therapy for these tumors.Endocrine Related Cancer 02/2014; DOI:10.1530/ERC-13-0398 · 4.91 Impact Factor
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ABSTRACT: Head and neck paragangliomas (HNPGLs) are rare neuroendocrine tumors belonging to the family of pheochromocytoma/paraganglioma neoplasms. Despite advances in understanding the pathogenesis of these tumors, the growth potential and clinical outcome of individual cases remains largely unpredictable. Over several decades, surgical resection has long been the treatment of choice for HNPGLs. However, increasing experience in various forms of radiosurgery has been reported to result in curative-like outcomes, even for tumors localized in the most inaccessible anatomical areas. The emergence of such new therapies challenges the traditional paradigm for the management of HNPGLs. This review will assist and guide physicians who encounter patients with such tumors, either from a diagnostic or therapeutic standpoint. This review will also particularly emphasize current and emerging knowledge in genetics, imaging, and therapeutic options, as well as the health-related quality of life for patients with HNPGLs.Endocrine Reviews 07/2014; 35(5):er20141026. DOI:10.1210/er.2014-1026 · 19.36 Impact Factor
Article: Hereditary Pheochromocytoma[Show abstract] [Hide abstract]
ABSTRACT: Introduction. Pheochromocytomas (PHEO) and paragangliomas (PGL) are rare neuroendocrine tumors with an estimated occurrence of 2 to 5 patients per million per year and an incidence of about 1 per 100 000 in the general population. These tumors may arise sporadically or be associated to various syndromes, namely multiple endocrine neoplasia type 2, neurofibromatosis type 1, Von Hippel-Lindau syndrome, and hereditary paraganglioma-pheochromocytoma syndromes. Objectives. This article aims to review the current epidemiology, pathogenesis, clinical presentation, and genetic aspects of syndromes associated with hereditary PHEO/PGL. Methods. The literature research, conducted at PubMed database, included review articles, published from February 2009 to February 2014, written in English or Portuguese, using as query: "Hereditary AND Pheochromocytoma." Conclusion. These tumors can be part of a myriad hereditary conditions that are not yet fully understood. Nevertheless, important systemic symptoms and even fatal outcomes can occur. Knowledge of these hereditary conditions can ensure a more efficient detection, treatment, and even prevention of these neuroectodermal tumors, thus new tests and studies should be conducted.International Journal of Surgical Pathology 06/2014; 22(5). DOI:10.1177/1066896914537683 · 0.96 Impact Factor