Reprogramming of tumor cell metabolism contributes to disease progression and resistance to therapy, but how this process is regulated on the molecular level is unclear. Here we report that Heat Shock Protein 90 (Hsp90)-directed protein folding in mitochondria controls central metabolic networks in tumor cells, including the electron transport chain, citric acid cycle, fatty acid oxidation, amino acid synthesis, and cellular redox status. Specifically, mitochondrial Hsp90, but not cytosolic Hsp90, binds and stabilizes the electron transport chain Complex II subunit succinate dehydrogenase-B, maintaining cellular respiration under low-nutrient conditions, and contributing to hypoxia-inducible factor-1α-mediated tumorigenesis in patients carrying succinate dehydrogenase-B mutations. Thus, Hsp90-directed proteostasis in mitochondria regulates tumor cell metabolism, and may provide a tractable target for cancer therapy.

Diagnosis of PPGLs using plasma or urinary free metabolites provides advantages of fewer false-positive results compared with commonly measured deconjugated metabolites. The plasma panel offers better diagnostic performance than either urinary panel for patients at high risk of disease and, with appropriate preanalytics, provides the test of choice. Measurements of methoxytyramine in urine show limited diagnostic utility compared with plasma.

The higher prevalence of hereditary, extra-adrenal, multifocal, and metastatic PPGLs in children than adults represents interrelated features that, in part, reflect the lower age of disease presentation of noradrenergic cluster 1 than adrenergic cluster 2 tumors. The differences in disease presentation are important to consider in children at risk for PPGLs due to a known mutation or previous history of tumor.

• A novel germ-l i n e PHD1 mutation causing heochromocytoma/paraganglioma and polycythemia. • Increased EPOR activity and inappropriate hypersensitivity of erythroid progenitors to EPO.

Objective Hypertension and symptoms of catecholamine excess are features of pheochromocytomas and paragangliomas (PPGLs). This prospective observational cohort study assessed whether differences in presenting features in patients tested for PPGLs might assist establishing likelihood of disease. Design and methods Patients were tested for PPGLs because of signs and symptoms, an incidental mass on imaging or routine surveillance due to previous history or hereditary risk. Patients with (n = 245) compared to without (n = 1820) PPGLs were identified on follow-up. Differences in presenting features were then examined to assess the probability of disease and relationships to catecholamine excess. Results Hyperhidrosis, palpitations, pallor, tremor and nausea were 30–90% more prevalent (P < 0.001) among patients with than without PPGLs, whereas headache, flushing and other symptoms showed little or no differences. Although heart rates were higher (P < 0.0001) in patients with than without PPGLs, blood pressures were not higher and were positively correlated to BMI, which was lower (P < 0.0001) in patients with than without PPGLs. From these differences in clinical features, a score system was established that indicated a 5.8-fold higher probability of PPGLs in patients with high than low scores. Higher scores among patients with PPGLs were associated, independently of tumor size, with higher biochemical indices of catecholamine excess. Conclusions This study identifies a complex of five signs and symptoms combined with lower BMI and elevated heart rate as key features in patients with PPGLs. Prevalences of these features, which reflect variable tumoral catecholamine production, may be used to triage patients according to likelihood of disease.

Paragangliomas (PGLs) are rare chromaffin cell tumors that can often be cured by resection. Although described for the first time in 1886 1 , the diagnosis of PGL remains a challenge, because patients do not present with characteristic signs and symptoms. If untreated, PGL can have a devastating outcome due to myocardial infarction, severe hypertension, stroke and/or arrhytmia caused by catecholamine excess. Even after proper diagnosis, the risk of metastatic disease remains. In recent years the opinion that metastatic disease is rare in PGL had to be revised, particularly in patients presenting with extra-adrenal PGL, with a PGL exceeding a size of 5 cm and/or carrying an SDHB germline mutation (especially for children and adolescents). In up to 10 % of patients, metastases are already present at diagnosis of PGL.Measurement of plasma and urinary metanephrine levels has long been used effectively in the diagnosis of PGL. Recently, a dopaminergic phenotype (excess dopamine, L-3,4-dihydroxyphenylalanine and or methoxytyramine) was recognized as a good indicator for metastatic disease. Vast progress in targeted PET imaging (e.g. 18 F-FDA, 18 F-FDOPA, 18 F-FDG) now allows for reliable early detection of metastatic disease. However, once metastatses are present, treatment options are limited. Survival of patients with metastatic PGL is variable. Depending on the study population the overall 5 year survival is 35-60 %, 2 .Here we review recent advances involving findings about the genetic background, the molecular pathogenesis, new diagnostic indicators, pathologic markers and emerging treatment options for metastatic PGL. DefinitionFollowing the definition of the world health organization, paragangliomas (PGLs) are chromaffin cell tumors developing from the sympathetic and parasympathetic ganglia throughout the abdomen and head and neck area. A PGL arising from the adrenal gland is called pheochromocytoma (PHEO). In addition, here we will distinguish between Corresponding author: Karel Pacak, M.D., Ph.D., D.Sc., Chief, Section on Medical Neuroendocrinology, Professor of Medicine, Reproductive and Adult Endocrinology Program, NICHD, NIH, Building 10, CRC, 1-East, Room 1-3140, 10 Center Drive, MSC-1109, Bethesda, Maryland 20892-1109. DISCLOSURE STATEMENT: The authors have nothing to disclose. 1 Carbidopa has been shown to increase the tumor-to-background ratio of 18 F-FDOPA uptake in PGL, particularly PHEO 68Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access Rule of 10 % OvercomePGL has long been considered as the disease of 10 % (10 % metastatic, 10 % f...

Mutations that drive the stabilization of hypoxia inducible factor 2α (HIF2α) and downstream pseudohypoxic signaling are known to predispose to the development of pheochromocytomas and paragangliomas (PPGLs). However, any role of HIF2α in predisposition to metastatic disease remains unclear. To assess such a role we combined gene-manipulations in pheochromocytoma cell lines with retrospective analyses of patient data and gene expression profiling in tumor specimens. Among 425 patients with PPGLs identified with mutations in tumor-susceptibility genes, those with tumors due to activation of pseudohypoxic pathways had a higher frequency of metastatic disease than those with tumors due to activation of kinase-signaling pathways, even without inclusion of patients with mutations in SDHB (18.6% vs. 4.3% in, p<0.0001). Three out of nine (33%) of patients with gain-of-function mutations in HIF2α had metastatic disease. In cell line studies, elevated expression of HIF2α enhanced cell proliferation and led to increased migration and invasion capacity. Moreover, HIF2α expression in HIF2α-deficient cells resulted in increased cell motility, diffuse cluster formation and emergence of pseudopodia indicating changes in cell adhesion and cytoskeletal remodeling. In a mouse liver metastasis model, HIF2α enhanced the metastatic load. Transcriptomics data revealed alterations in focal adhesion and extracellular matrix-receptor interactions in HIF2α-mutated PPGLs. Our translational findings demonstrate that HIF2α supports pro-metastatic behavior in PPGLs, though other factors remain critical for subsequent transition to metastasis. We identified LAMB1 and COL4A2 as new potential therapeutic targets for HIF2α-driven PPGLs. Identified HIF2α downstream targets might open a new therapeutic window for aggressive HIF2α-expressing tumors.

ContextMeasurements of plasma methoxytyramine, the O-methylated dopamine metabolite, are useful for detecting rare dopamine-producing pheochromocytomas and paragangliomas (PPGLs) and head and neck paragangliomas (HNPGLs), but utility for screening beyond that achieved using standard measurements of normetanephrine and metanephrine is unclear.ObjectiveEvaluation of the additional utility of methoxytyramine compared to plasma normetanephrine and metanephrine for diagnosis of PPGLs and HNPGLs.DesignComparative prospective study.MethodsComparison of mass spectrometric-based measurements of plasma methoxytyramine, normetanephrine and metanephrine in 1963 patients tested for PPGLs at six tertiary medical centers according to reference intervals verified in 423 normotensive and hypertensive volunteers.ResultsOf the screened patients, 213 had PPGLs and 38 HNPGLs. Using an upper cut-off of 0.10 nmol/L for methoxytyramine, 0.45 nmol/L for metanephrine and age-specific upper cut-offs for normetanephrine, diagnostic sensitivity with the addition of methoxytyramine increased from 97.2% to 98.6% for patients with PPGLs and from 22.1% to 50.0% for patients with HNPGLs, with a small decrease in specificity from 95.9% to 95.1%. Addition of methoxytyramine did not significantly alter areas under receiver operating characteristic curves for patients with PPGLs (0.984 vs 0.991), but did increase (P < 0.05) areas for patients with HNPGLs (0.627 vs 0.801). Addition of methoxytyramine also increased the proportion of patients with PPGLs who showed highly positive predictive elevations of multiple metabolites (70.9% vs 49.3%).ConclusionsWhile the benefit of additional measurements of plasma methoxytyramine for the detection of PPGLs is modest, the measurements do assist with positive confirmation of disease and are useful for the detection of HNPGLs.