Beta-blockers are associated with increased risk of first cardiovascular events in non-diabetic hypertensive elderly patients.

PURPOSE: Although treatment should be considered for elderly patients with hypertension (HTN), the effectiveness of beta-blockers (BBs) compared with other medications is less clear. This study's objective is to assess the relative effectiveness of BBs in elderly primary prevention patients with uncomplicated HTN. METHODS: This is a population-based nested case-control study. The cohort is composed of 94,844 elderly patients followed through 2009 and diagnosed with HTN between 2000 and 2004, without recent antecedents of diabetes, renal disease, or cardiovascular disease (CVD). Individuals with a CVD outcome were considered cases, and controls were matched to cases according to age, sex, date of cohort entry, and comorbidity index. Patients whose treatment included a BB were compared with patients on other HTN drug(s). RESULTS: The BB use by patients was associated with an increased risk for CVD events (odds ratio (OR) = 1.36, 95%CI: 1.31-1.40) compared with patients using antihypertensive therapies without BBs. Sensitivity analyses suggest that this increased risk is not due to differences in prescription patterns on the basis of perceived disease severity. CONCLUSIONS: In real-world settings, antihypertensive therapies that include BBs are associated with less effective prevention of adverse outcomes in elderly hypertensive patients in primary prevention compared with antihypertensive therapies without BBs. Pending further studies, we recommend caution when prescribing BBs in primary prevention except when otherwise indicated.

An unusual ostensible example of intraoral basal cell carcinoma.

An example of oral basal cell carcinoma is presented originating on the posterior mandibular mucosa and gingiva of a 67-year-old female. Histologically, it featured a multifocal pattern. It recurred eight times in a period of 20 years. Tissue samples of the tumor were evaluated with monoclonal antibody Ber-EP4 and were compared with examples of oral mucosa, skin, oral and cutaneous squamous cell carcinoma, peripheral ameloblastoma, ameloblastoma and cutaneous basal cell carcinoma (BCC). Only neoplastic basal cells showed positive immunohistochemical staining. Additionally, microdissected neoplastic areas were evaluated for loss of heterozygosity (LOH) of the PTCH gene with markers D9S303, D9S252 and D9S287. PTCH gene mutations are reported in patients with Gorlin syndrome and sporadic cutaneous BCCs. Loss of one allele was observed with all three markers. Examples of conventional ameloblastomas did not show evidence of LOH. These observations support the inclusion of BCC in the differential diagnosis of appropriate oral mucosal neoplasms.

Proteomic profiling of von Hippel-Lindau syndrome and multiple endocrine neoplasia type 2 pheochromocytomas reveals different expression of chromogranin B.

Pheochromocytomas are catecholamine-producing tumors that can occur in the context of von Hippel-Lindau syndrome (VHL) and multiple endocrine neoplasia type 2 (MEN2). Pheochromocytomas in these two syndromes differ in histopathological features, catecholamine metabolism, and clinical phenotype. To further investigate the nature of these differences, we compared the global protein expressions of 8 MEN2A-associated pheochromocytomas with 11 VHL-associated pheochromocytomas by two-dimensional gel electrophoresis proteomic profiling followed by sequencing and identification of differentially expressed proteins. Although both types of pheochromocytoma shared similarities in their protein expression patterns, the expression of several proteins was distinctly different between VHL- and MEN2A-associated pheochromocytomas. We identified several of these differentially expressed proteins. One of the proteins with higher expression in MEN2-associated tumors was chromogranin B, of which the differential expression was confirmed by western blot analysis. Our results expand the evidence for proteomic differences between these two tumor entities, and suggest that VHL-associated pheochromocytomas may be deficient in fundamental machinery for catecholamine storage. In light of these new findings, as well as existing evidence for differences between both types of pheochromocytomas, we propose that these tumors may have different developmental origins.

High frequency of SDHB germline mutations in patients with malignant catecholamine-producing paragangliomas: implications for genetic testing.

CONTEXT: Adrenal and extraadrenal paragangliomas are tumors of chromaffin cells that are usually benign but that may also develop into malignant disease. Mutations of the gene for succinate dehydrogenase subunit B (SDHB) are associated with a high risk of malignancy, but establishing the precise contribution requires relatively large numbers of patients with well-defined malignancy. OBJECTIVE: We assessed the prevalence of SDHB mutations in a series of patients with malignant paraganglioma. DESIGN: SDHB mutation testing was carried out in 44 consecutive patients with malignant paraganglioma. Clinical characteristics of patients with malignant disease due to SDHB mutations were compared with those without mutations. RESULTS: Pathogenic SDHB mutations were found in 13 of the 44 patients (30%). Close to one third of patients had metastases originating from an adrenal primary tumor, compared with a little over two thirds from an extraadrenal tumor. Among the latter patients, the frequency of SDHB mutations was 48%. CONCLUSION: This study establishes that missense, nonsense, frameshift, and splice site mutations of the SDHB gene are associated with about half of all malignancies originating from extraadrenal paragangliomas. The high frequency of SDHB germline mutations among patients with malignant disease, particularly when originating from an extraadrenal paraganglioma, may justify a high priority for SDHB germline mutation testing in these patients.

Emergencies caused by pheochromocytoma, neuroblastoma, or ganglioneuroma.

Pheochromocytoma may lead to important emergency situations, ranging from cardiovascular emergencies to acute abdomen and multiorgan failure. It is vital to think about this disease in any emergency situation when conventional therapy fails to achieve control or symptoms occur that do not fit the initial diagnosis. The importance of keeping this diagnosis in minds is underscored by the fact that, in 50% of pheochromocytoma patients, the diagnosis is initially overlooked. Two other tumors of the sympathetic nervous system, neuroblastoma and ganglioneuroma, are less commonly associated with emergency conditions. If they occur, they are often linked to catecholamine excess, paraneoplastic phenomena, or local tumor mass effect.

Somatic VHL gene alterations in MEN2-associated medullary thyroid carcinoma.

BACKGROUND: Germline mutations in RET are responsible for multiple endocrine neoplasia type 2 (MEN2), an autosomal dominantly inherited cancer syndrome that is characterized by medullary thyroid carcinoma (MTC), pheochromocytoma, and parathyroid hyperplasia/adenoma. Recent studies suggest a "second hit" mechanism resulting in amplification of mutant RET. Somatic VHL gene alterations are implicated in the pathogenesis of MEN2 pheochromocytomas. We hypothesized that somatic VHL gene alterations are also important in the pathogenesis of MEN2-associated MTC. METHODS: We analyzed 6 MTCs and 1 C-cell hyperplasia (CCH) specimen from 7 patients with MEN2A and RET germline mutations in codons 609, 618, 620, or 634, using microdissection, microsatellite analysis, phosphorimage densitometry, and VHL mutation analysis. RESULTS: First, we searched for allelic imbalance between mutant and wild-type RET by using the polymorphic markers D10S677, D10S1239, and RET on thyroid tissue from these patients. Evidence for RET amplification by this technique could be demonstrated in 3 of 6 MTCs. We then performed LOH analysis using D3S1038 and D3S1110 which map to the VHL gene locus at 3p25/26. VHL gene deletion was present in 3 MTCs. These 3 MTCs also had an allelic imbalance between mutant and wild-type RET. Mutation analysis of the VHL gene showed a somatic frameshift mutation in 1 MTC that also demonstrated LOH at 3p25/26. In the 2 other MTCs with allelic imbalance of RET and somatic VHL gene deletion, no somatic VHL mutation could be detected. The CCH specimen did neither reveal RET imbalance nor somatic VHL gene alterations. CONCLUSION: These data suggest that a RET germline mutation is necessary for development of CCH, that allelic imbalance between mutant and wild-type RET may set off tumorigenesis, and that somatic VHL gene alterations may not play a major role in tumorigenesis of MEN2A-associated MTC.

Gene expression profiling of benign and malignant pheochromocytoma.

There are currently no reliable diagnostic and prognostic markers or effective treatments for malignant pheochromocytoma. This study used oligonucleotide microarrays to examine gene expression profiles in pheochromocytomas from 90 patients, including 20 with malignant tumors, the latter including metastases and primary tumors from which metastases developed. Other subgroups of tumors included those defined by tissue norepinephrine compared to epinephrine contents (i.e., noradrenergic versus adrenergic phenotypes), adrenal versus extra-adrenal locations, and presence of germline mutations of genes predisposing to the tumor. Correcting for the confounding influence of noradrenergic versus adrenergic catecholamine phenotype by the analysis of variance revealed a larger and more accurate number of genes that discriminated benign from malignant pheochromocytomas than when the confounding influence of catecholamine phenotype was not considered. Seventy percent of these genes were underexpressed in malignant compared to benign tumors. Similarly, 89% of genes were underexpressed in malignant primary tumors compared to benign tumors, suggesting that malignant potential is largely characterized by a less-differentiated pattern of gene expression. The present database of differentially expressed genes provides a unique resource for mapping the pathways leading to malignancy and for establishing new targets for treatment and diagnostic and prognostic markers of malignant disease. The database may also be useful for examining mechanisms of tumorigenesis and genotype-phenotype relationships. Further progress on the basis of this database can be made from follow-up confirmatory studies, application of bioinformatics approaches for data mining and pathway analyses, testing in pheochromocytoma cell culture and animal model systems, and retrospective and prospective studies of diagnostic markers.

Biochemical and clinical manifestations of dopamine-producing paragangliomas: utility of plasma methoxytyramine.

Measurements of plasma-free normetanephrine and metanephrine provide a sensitive test for diagnosis of pheochromocytoma but may fail to detect tumors that produce predominantly dopamine. Such tumors are extremely rare, usually found as extraadrenal paragangliomas. This report describes measurements of plasma concentrations of free methoxytyramine, the O-methylated metabolite of dopamine, in 120 patients with catecholamine-producing tumors, including nine with extraadrenal paragangliomas secreting predominantly dopamine. In seven of these nine patients, tumors were found incidentally or secondary to the space-occupying complications of the lesions. Plasma concentrations of free methoxytyramine and dopamine were increased in all nine patients, including two with normal plasma and urinary normetanephrine and metanephrine and normal urinary outputs of dopamine. Relative increases above normal for plasma methoxytyramine (104-fold) and dopamine (56-fold) were much greater (P < 0.001) than those for urinary dopamine (3-fold). Insensitivity of the latter for identification of dopamine-secreting tumors was due to dependence of the urinary amine on renal extraction and decarboxylation of circulating 3,4-dihydroxyphenylalanine. Measurements of plasma-free methoxytyramine, in addition to normetanephrine and metanephrine, are unlikely to improve diagnosis of pheochromocytomas in hypertensive patients with symptoms of catecholamine excess but may be useful in selected patients for identification of tumors that produce predominantly dopamine.

Differential expression of erythropoietin and its receptor in von hippel-lindau-associated and multiple endocrine neoplasia type 2-associated pheochromocytomas.

Pheochromocytoma is a neuroendocrine tumor associated with a variety of genetic disorders, which include von Hippel-Lindau disease (VHL), multiple endocrine neoplasia type 2 (MEN 2), neurofibromatosis type 1, hereditary paraganglioma, and succinate dehydrogenase gene-related tumors. Previous studies of VHL-associated and MEN 2-associated pheochromocytomas suggest morphological, biochemical, and clinical differences exist among the tumors, but the process by which they develop remains unclear. Studies in other VHL-associated tumors suggest that VHL gene deficiency causes coexpression of erythropoietin (Epo) and its receptor (Epo-R), which facilitates tumor growth. The objective of this study was to understand the different process of tumorigenesis for VHL and MEN 2-associated pheochromocytomas. Ten pheochromocytomas (VHL patients n = 5, MEN 2 patients n = 5) were examined for the presence or absence of Epo and Epo-R using Western blot, immunohistochemistry, and RT-PCR analyses. Coexpression of Epo and Epo-R was found in all five VHL-associated pheochromocytomas; in contrast, expression of Epo-R, but not Epo, was documented in all five MEN 2-associated pheochromocytomas. Expression of Epo appears to be a result of VHL gene deficiency, possibly through activation of the hypoxia inducible factor-1 pathway, whereas Epo-R is an embryonal marker whose sustained expression in both VHL- and MEN 2-associated pheochromocytomas reflects an arrest or defect in development. These findings suggest an alternative process of tumorigenesis in VHL- and MEN 2-associated pheochromocytomas and implicate Epo as a clinical biomarker to differentiate these tumors.

Different expression of catecholamine transporters in phaeochromocytomas from patients with von Hippel-Lindau syndrome and multiple endocrine neoplasia type 2.

OBJECTIVE: Phaeochromocytomas in patients with multiple endocrine neoplasia type 2 (MEN 2) produce adrenaline, whereas those with von Hippel-Lindau (VHL) syndrome do not. This study assessed whether these distinctions relate to differences in expression of the transporters responsible for uptake and storage of catecholamines - the noradrenaline transporter and the vesicular monoamine transporters (VMAT 1 and VMAT 2). METHODS: Tumour tissue and plasma samples were obtained from 31 patients with hereditary phaeochromocytoma - 18 with VHL syndrome and 13 with MEN 2. We used quantitative PCR, Western blotting, electron microscopy, immunohistochemistry and measurements of plasma and tumour catecholamines to assess differences in expression of the transporters in noradrenaline-producing vs adrenaline-producing hereditary tumours. These differences were compared with those in a further group of 26 patients with non-syndromic phaeochromocytoma. RESULTS: Adrenaline-producing phaeochromocytomas in MEN 2 patients expressed more noradrenaline transporter mRNA and protein than noradrenaline-producing tumours in VHL patients. In contrast, there was greater expression of VMAT 1 in VHL than MEN 2 tumours, while expression of VMAT 2 did not differ significantly. These differences were associated with larger numbers of storage vesicles and higher tissue contents of catecholamines in MEN 2 than in VHL tumours. Differences in expression of the noradrenaline transporter were weaker, and those of VMAT 1 and VMAT 2 stronger, in noradrenaline and adrenaline-producing non-syndromic than in hereditary tumours. CONCLUSIONS: The findings show that, in addition to differences in catecholamine biosynthesis, phaeochromocytomas in MEN 2 and VHL syndrome also differ in expression of the transporters responsible for uptake and vesicular storage of catecholamines.

Malignant pheochromocytoma: current status and initiatives for future progress.

Pheochromocytomas are rare catecholamine-producing neuroendocrine tumors that are usually benign, but which may also present as or develop into a malignancy. Predicting such behavior is notoriously difficult and there are currently no curative treatments for malignant tumors. This report follows from a workshop at the Banbury Conference Center, Cold Spring Harbor, New York, on the 16th-18th November 2003, held to review the state of science and to facilitate future progress in the diagnosis and treatment of malignant pheochromocytoma. The rarity of the tumor and the resulting fragmented nature of studies, typically involving small numbers of patients, represent limiting factors to the development of effective treatments and diagnostic or prognostic markers for malignant disease. Such development is being facilitated by the availability of new genomics-based tools, but for such approaches to succeed ultimately requires comprehensive clinical studies involving large numbers of patients, stringently collected clinical data and tumor samples, and interdisciplinary collaborations among multiple specialist centers. Nevertheless, the well-characterized hereditary basis and the unique functional nature of these neuroendocrine tumors provide a useful framework that offers advantages for establishing the pathways of tumorigenesis and malignancy. Such findings may have relevance for understanding the basis of other more common malignancies where similar frameworks are not available. As the relevant pathways leading to pheochromocytoma are established it should be possible to take advantage of the new generation of drugs being developed to target specific pathways in other malignancies. Again the success of this will require well-designed and coordinated multi-center studies.

New insights into the genetics of familial chromaffin cell tumors.

We review genetic aspects and recent advances in our understanding of the molecular pathogenesis of familial chromaffin cell tumors (pheochromocytoma, paraganglioma). About 10 percent of pheochromocytomas are familial and occur as part of multiple endocrine neoplasia type 2 (MEN 2), von Hippel-Lindau (VHL) disease, and neurofibromatosis type 1 (NF 1). A subset of paragangliomas, tumors that can also produce and secrete catecholamines, are also familial and occur in patients with germline mutations in genes that encode subunits of the mitochondrial complex II. The precise molecular mechanisms underlying the pathogenesis of chromaffin cell tumors remain widely unknown, although recent studies in hereditary tumors help elucidate their development. In MEN 2, overrepresentation of mutant RET in selected adrenomedullary cells may be an important mechanism in initiating the formation of a pheochromocytoma. In VHL disease, pheochromocytoma development appears to occur according to Knudson's two-hit model, a VHL germline mutation and wildtype allelic deletion. Tumorigenesis of NF1-associated pheochromocytomas remains unknown, as does tumor formation (i.e., carotid body tumor) in patients with germline mutations in SDHB, SDHC, and SDHD, genes that encode subunits of the mitochondrial complex II, the smallest complex in the respiratory chain. Many genetic alterations have been found in sporadic chromaffin cell tumors. However, at present such genetic changes are difficult to place into context with regard to tumor formation and progression.

Hypotension in a woman with a metastatic dopamine-secreting carotid body tumor.

OBJECTIVE: To describe a woman with metastatic carotid body tumor in whom hypotension occurred in the setting of exceedingly high plasma dopamine levels. METHODS: We present a case report and review the literature on the topic of dopamine-secreting paraganglioma or pheochromocytoma. RESULTS: A previously healthy 40-year-old Asian woman noted difficulty with swallowing and hoarseness. No neck mass was visible, and she had no symptoms of catecholamine excess and no family history of endocrine disorders or malignant disease. Indirect laryngoscopy revealed a paralyzed left vocal cord and a nonulcerating mass in the left parapharyngeal space. An initial needle biopsy was interpreted as undifferentiated carcinoma. After a second biopsy, this mass was diagnosed as a neuroendocrine tumor, consistent with paraganglioma. The patient underwent surgical resection and radiation therapy (total dose, 40 Gy), after which she remained asymptomatic for 11 years. Then loss of weight, fatigue, nausea, and hypotensive episodes (blood pressures as low as 70/35 mm Hg) prompted whole-body imaging with bone scans, computed tomography, and magnetic resonance imaging, which disclosed several lesions in the liver, lungs, and spine, suggestive of metastatic disease. The adrenal glands were unremarkable. A metaiodobenzylguanidine scan with use of (131)I was negative. Liver biopsy of a hypodense lesion revealed a neuroendocrine tumor by histologic and immunohistochemical studies. Because of the patient's history, malignant paraganglioma was diagnosed. The tumor secreted predominantly dopamine at extraordinary levels (plasma concentration 27,942 pg/mL; normal, <30). The patient died before further treatment could be initiated. CONCLUSION: Carotid body tumors usually do not secrete catecholamines but frequently metastasize. During progression, these neuroendocrine tumors may become able to produce and secrete selected catecholamines such as dopamine. Dopamine can lower the blood pressure rather than causing hypertension, even though hypertension is one of the main symptoms of a pheochromocytoma.

Evaluation of Tc-99m-labeled glycoprotein IIb/IIIa receptor antagonist DMP444 SPECT in patients with infective endocarditis.

PURPOSE: Infective endocarditis (IE) is characterized by aggregation of activated platelets, fibrin, and bacteria. DMP444, a high-affinity glycoprotein IIb/IIIa receptor antagonist, binds to the fibrinogen-binding domain of activated platelets, depicting a key feature of IE. Tc-99m DMP444 scintigraphy was studied in a group of patients with possible IE. METHODS: Tc-99m DMP444 (600 MBq; 16 mCi) planar and SPECT images of the heart were recorded in patients with possible IE for as long as 6 hours after injection. Results were compared to echocardiography and the Duke classification. RESULTS: Sixteen patients (age range, 37 to 78 years) participated. DMP444 imaging was positive on SPECT in five patients, and all had definite endocarditis (affecting both prosthetic and native valves). Eleven patients were DMP444 negative, seven with no proof of IE. The remaining four patients were classified as having IE, but three had been receiving adequate intravenous antibiotic regimens for > or = 2 weeks at the time of scintigraphy and one had Q-fever endocarditis. CONCLUSIONS: DMP444 SPECT allows in vivo visualization of IE if it is performed within 1 to 2 weeks after the start of antibiotic treatment. Given the high affinity of DMP444 for activated platelets, the results indicate the involvement of activated platelets in early IE.

The adequacy of pharmaceutical treatment of schizophrenia in Quebec varies with age, but is not influenced by sex or neighbourhood deprivation.

OBJECTIVE: Though high discontinuation rates for antipsychotics (APs) by patients with schizophrenia are frequently reported, the percentage of patients receiving pharmaceutical treatment for schizophrenia in routine practice in accordance with international clinical guidelines is unknown. Further, it is unknown if these rates are influenced by levels of neighbourhood deprivation or by a patient's age or sex. Our study aims to investigate if inequalities in AP treatment could be observed between patients living in neighbourhoods with the highest levels of material and social deprivation and those with the lowest deprivation levels, between patients from different age groups, or between men and women. METHODS: We conducted a secondary analysis of medical-administrative data of a cohort of adult patients in the province of Quebec with a medical contact for schizophrenia in a 2-year period (2004-2005). We assessed the proportion of patients that filled at least 1 prescription for an AP and received adequate pharmaceutical treatment, defined as being in possession of APs at least 80% of the time as outpatients during a 2-year follow-up period. RESULTS: Among the 30 544 study patients, 88.5% filled at least 1 prescription for an AP, and 67.5% of the treated patients received adequate treatment. Though no clinically significant differences were observed by deprivation or sex, younger age was associated with lower proportions of patients receiving adequate treatment (46% of treated patients aged between 18 and 29 years, compared with 72% aged between 30 and 64 years, and 77% aged 65 years and over). CONCLUSIONS: In Quebec's routine practice, over 70% of treated patients aged 30 and over received adequate pharmacological treatment, regardless of sex or neighbourhood socioeconomic status. In contrast, in patients aged between 18 and 29 years this percentage was 47%. This is a discouraging finding, especially because optimal treatment in the early phase of disease is reported to result in the best long-term outcomes.

Objectif : Bien que des taux élevés d'interruption des antipsychotiques (AP) par des patients souffrant de schizophrénie soient souvent rapportés, le pourcentage des patients recevant un traitement pharmaceutique pour la schizophrénie dans la pratique régulière, conformément aux lignes directrices cliniques internationales, est inconnu. En outre, il n'est pas déterminé si ces taux sont influencés par les niveaux de pauvreté du quartier ou par l'âge ou le sexe des patients. Notre étude vise à rechercher si des inégalités du traitement par AP peuvent s'observer entre les patients habitant les quartiers les plus défavorisés au niveau matériel et social et les quartiers moins défavorisés, entre les patients de différents groupes d'âge, ou entre hommes et femmes. Méthodes : Nous avons mené une analyse secondaire des données administratives médicales d'une cohorte de patients adultes de la province de Québec ayant recouru à un service médical pour schizophrénie durant une période de 2 ans (2004­2005). Nous avons évalué la proportion de patients qui ont fait remplir au moins 1 ordonnance d'AP et reçu un traitement pharmaceutique adéquat, défini comme étant en possession d'AP au moins 80 % du temps comme patients externes durant une période de suivi de 2 ans. Résultats : Parmi les 30 544 patients de l'étude, 88,5 % ont fait remplir au moins une ordonnance d'AP, et 67,5 % des patients traités ont reçu un traitement adéquat. Bien que des différences cliniquement significatives n'aient pas été observées selon la pauvreté ou le sexe, le jeune âge était associé aux proportions plus faibles de patients recevant un traitement adéquat (46 % des patients traités âgés entre 18 et 29 ans, comparé à 72 % entre 30 et 64 ans, et à 77 % de 65 ans et plus). Conclusions : Dans la pratique régulière, au Québec, plus de 70 % des patients traités âgés de 30 ans et plus ont reçu un traitement pharmacologique adéquat, sans égard au sexe ou au statut socioéconomique du quartier. Par contre, chez les patients âgés entre 18 et 29 ans, ce pourcentage était de 47 %. Ce résultat est décourageant, surtout parce que le traitement optimal dans la première phase de la maladie est reconnu obtenir les meilleurs résultats à long terme.

Increased uptake of [¹²³I]meta-iodobenzylguanidine, [¹8F]fluorodopamine, and [³H]norepinephrine in mouse pheochromocytoma cells and tumors after treatment with the histone deacetylase inhibitors.

[¹³¹I]meta-iodobenzylguanidine ([¹³¹I]MIBG) is the most commonly used treatment for metastatic pheochromocytoma and paraganglioma. It enters the chromaffin cells via the membrane norepinephrine transporter; however, its success has been modest. We studied the ability of histone deacetylase (HDAC) inhibitors to enhance [¹²³I]MIBG uptake by tumors in a mouse metastatic pheochromocytoma model. HDAC inhibitors are known to arrest growth, induce differentiation and apoptosis in various cancer cells, and further inhibit tumor growth. We report the in vitro and in vivo effects of two HDAC inhibitors, romidepsin and trichostatin A, on the uptake of [(3)H]norepinephrine, [¹²³I]MIBG, and [(18)F]fluorodopamine in a mouse model of metastatic pheochromocytoma. The effects of both inhibitors on norepinephrine transporter activity were assessed in mouse pheochromocytoma (MPC) cells by using the transporter-blocking agent desipramine and the vesicular-blocking agent reserpine. HDAC inhibitors increased [(3)H]norepinephrine, [¹²³I]MIBG, and [(18)F]fluorodopamine uptake through the norepinephrine transporter in MPC cells. In vivo, inhibitor treatment resulted in significantly increased uptake of [(18)F]fluorodopamine positron emission tomography (PET) in pheochromocytoma liver metastases (19.1 ± 3.2% injected dose per gram of tumor (%ID/g) compared to liver metastases in pretreatment scans 5.9 ± 0.6%; P<0.001). Biodistribution analysis after inhibitors treatment confirmed the PET results. The uptake of [(123)I]MIBG was significantly increased in liver metastases 9.5 ± 1.1% compared to 3.19 ± 0.4% in untreated control liver metastases (P<0.05). We found that HDAC inhibitors caused an increase in the amount of norepinephrine transporter expressed in tumors. HDAC inhibitors may enhance the therapeutic efficacy of [(131)I]MIBG treatment in patients with advanced malignant pheochromocytoma and paraganglioma.

Gender-related differences in the clinical presentation of malignant and benign pheochromocytoma.

Signs and symptoms associated with pheochromocytomas are predominantly caused by catecholamine excess, but tend to be highly variable and non-specific. In this study, we evaluated 23 male and 35 female pheochromocytoma patients for symptoms and signs of pheochromocytoma with special regard to gender-related differences in presentation. Total symptom score comparison between genders showed significant differences (12.0 vs. 7.8, P-value 0.0001). Female patients reported significantly more headache (80% vs. 52%), dizziness (83% vs. 39%), anxiety (85% vs. 50%), tremor (64% vs. 33%), weight change (88% vs. 43%), numbness (57% vs. 24%), and changes in energy level (89% vs. 64%). Females and males displayed comparable biochemical phenotypes (60% and 65% noradrenergic phenotype, respectively). Use of alpha- and/or beta-blockade between males and females did not differ significantly. Subgroup analyses and multiple regression analysis revealed gender differences to be irrespective of benign or malignant disease, use of adrenoceptor-blockade, age and biochemical phenotype. We conclude female patients have significantly more self-reported pheochromocytoma signs and symptoms than male patients irrespective of biochemical phenotype and tumor presentation which may be related to distinct catecholamine receptor sensitivity. Clinicians should be aware of these complaints in female pheochromocytoma patients and offer adequate treatment if indicated.

Pheochromocytoma catecholamine phenotypes and prediction of tumor size and location by use of plasma free metanephrines.

BACKGROUND: Measurements of plasma free metanephrines (normetanephrine and metanephrine) provide a useful test for diagnosis of pheochromocytoma and may provide other information about the nature of these tumors. METHODS: We examined relationships of tumor size, location, and catecholamine content with plasma and urinary metanephrines or catecholamines in 275 patients with pheochromocytoma. We then prospectively examined whether measurements of plasma free metanephrines could predict tumor size and location in an additional 16 patients. RESULTS: Relative proportions of epinephrine and norepinephrine in tumor tissue were closely matched by relative increases of plasma or urinary metanephrine and normetanephrine, but not by epinephrine and norepinephrine. Tumor diameter showed strong positive relationships with summed plasma concentrations or urinary outputs of metanephrine and normetanephrine (r = 0.81 and 0.77; P <0.001), whereas relationships with plasma or urinary catecholamines were weaker (r = 0.41 and 0.44). All tumors in which increases in plasma metanephrine were >15% of the combined increases of normetanephrine and metanephrine either had adrenal locations or appeared to be recurrences of previously resected adrenal tumors. Measurements of plasma free metanephrines predicted tumor diameter to within a mean of 30% of actual diameter, and high plasma concentrations of free metanephrine relative to normetanephrine accurately predicted adrenal locations. CONCLUSIONS: Measurements of plasma free metanephrines not only provide information about the likely presence or absence of a pheochromocytoma, but when a tumor is present, can also help predict tumor size and location. This additional information may be useful for clinical decision-making during tumor localization procedures.

Expression of the noradrenaline transporter and phenylethanolamine N-methyltransferase in normal human adrenal gland and phaeochromocytoma.

Expression of the noradrenaline transporter (NAT) was examined in normal human adrenal medulla and phaeochromocytoma by using immunohistochemistry and confocal microscopy. The enzymes tyrosine hydroxylase (TH) and phenylethanolamine N-methyltransferase (PNMT) were used as catecholamine biosynthetic markers and chromogranin A (CGA) as a marker for secretory granules. Catecholamine content was measured by using high performance liquid chromatography (HPLC). In normal human adrenal medulla (n=5), all chromaffin cells demonstrated strong TH, PNMT and NAT immunoreactivity. NAT was co-localized with PNMT and was located within the cytoplasm with a punctate appearance. Human phaeochromocytomas demonstrated strong TH expression (n=20 samples tested) but variable NAT and PNMT expression (n=24). NAT immunoreactivity ranged from absent (n=3) to weak (n=10) and strong (n=11) and, in some cases, occupied an apparent nuclear location. Unlike the expression seen in normal human adrenal medullary tissue, NAT expression was not consistently co-localized with PNMT. PNMT also showed highly variable expression that was poorly correlated with tumour adrenaline content. Immunoreactivity for CGA was colocalized with NAT within the cytoplasm of normal human chromaffin cells (n=4). This co-localization was not consistent in phaeochromocytoma tumour cells (n=7). The altered pattern of expression for both NAT and PNMT in phaeochromocytoma indicates a significant disruption in the regulation and possibly in the function of these proteins in adrenal medullary tumours.

Downregulation of metastasis suppressor genes in malignant pheochromocytoma.

There is no reliable method currently available to predict malignant potential of pheochromocytoma based on conventional histology or genetic, molecular or immunohistochemical markers. Metastasis suppressor genes affect the spread of several cancers and, therefore, may provide promise as prognostic markers or therapeutic targets for malignant pheochromocytoma. We hypothesized that the downregulation of metastasis suppressor genes in malignant pheochromocytoma may play a role in malignant behavior. We applied quantitative real-time polymerase chain reaction (QRT-PCR) to 11 metastasis suppressor genes. These genes are known to be involved in the regulation of important cancer-related cellular events, such as cell growth regulation and apoptosis (nm23-H1, TIMP-1, TIMP-2, TIMP-3, TIMP-4, TXNIP and CRSP-3), cell-cell communication (BRMS-1), invasion (CRMP-1) and cell adhesion (E-Cad and KiSS1). The study included 15 benign and 10 malignant pheochromocytomas. Six metastasis suppressor genes (nm23-H1, TIMP-4, BRMS-1, TXNIP, CRSP-3 and E-Cad) were downregulated significantly in malignant compared to benign pheochromocytoma (p < 0.05, Mann-Whitney U-test). We applied a non-linear rule using median malignant value (MMV) as a threshold to use metastasis suppressor genes to distinguish malignant from benign samples. After cross-validation, the non-linear rule produced no errors in 10 malignant samples and 3 errors in the 15 benign samples, with an overall error rate of 12%. These results suggest that downregulation of metastasis suppressor genes reflect malignant pheochromocytoma with a high degree of sensitivity. Thus, we conclude that altered function of these metastasis suppressor gene pathways may play an important role in the malignant behavior of pheochromocytoma.