Succinate Dehydrogenase Complex Subunit B Research Articles

Neuroprotective effect of ginsenoside Re on drosophila model of Parkinson's disease

This study aims to explore the neuroprotective mechanism of ginsenoside Re(GS-Re) on drosophila model of Parkinson's disease(PD) induced by rotenone(Rot). To be specific, Rot was used to induce PD in drosophilas. Then the drosophilas were grouped and respectively treated(GS-Re: 0.1, 0.4, 1.6 mmol·L~(-1); L-dopa: 80 μmol·L~(-1)). Life span and crawling ability of drosophilas were determined. The brain antioxidant activity [content of catalase(CAT), malondialdehyde(MDA), reactive oxygen species(ROS), superoxide dismutase(SOD)], dopamine(DA) content, and mitochondrial function [content of adenosine triphosphate(ATP), NADH:ubiquinone oxidoreductase subunit B8(NDUFB8) Ⅰ activity, succinate dehydrogenase complex, subunit B(SDHB) Ⅱ activity] were detected by enzyme-linked immunosorbent assay(ELISA). The number of DA neurons in the brains of drosophilas was measured with the immunofluorescence method. The levels of NDUFB8 Ⅰ, SDHB Ⅱ, cytochrome C(Cyt C), nuclear factor-E2-related factor 2(Nrf2), heme oxygenase-1(HO-1), B-cell lymphoma/leukemia 2(Bcl-2)/Bcl-2-assaciated X protein(Bax), and cleaved caspase-3/caspase-3 in the brain were detected by Western blot. The results showed that model group [475 μmol·L~(-1) Rot(IC_(50))] demonstrated significantly low survival rate, obvious dyskinesia, small number of neurons and low DA content in the brain, high ROS level and MDA content, low content of SOD and CAT, significantly low ATP content, NDUFB8 Ⅰ activity, and SDHB Ⅱ activity, significantly low expression of NDUFB8 Ⅰ, SDHB Ⅱ, and Bcl-2/Bax, large amount of Cyt C released from mitochondria to cytoplasm, low nuclear transfer of Nrf2, and significantly high expression of cleaved caspase-3/caspase-3 compared with the control group. GS-Re(0.1, 0.4, and 1.6 mmol·L~(-1)) significantly improved the survival rate of PD drosophilas, alleviated the dyskinesia, increased DA content, reduced the loss of DA neurons, ROS level, and MDA content in brain, improved content of SOD and CAT and antioxidant activity in brain, maintained mitochondrial homeostasis(significantly increased ATP content and activity of NDUFB8 Ⅰ and SDHB Ⅱ, significantly up-regulated expression of NDUFB8 Ⅰ, SDHB Ⅱ, and Bcl-2/Bax), significantly reduced the expression of Cyt C, increased the nuclear transfer of Nrf2, and down-regulated the expression of cleaved caspase-3/caspase-3. In conclusion, GS-Re can significantly relieve the Rot-induced cerebral neurotoxicity in drosophilas. The mechanism may be that GS-Re activates Keap1-Nrf2-ARE signaling pathway by maintaining mitochondrial homeostasis, improves antioxidant capacity of brain neurons, then inhibits mitochondria-mediated caspase-3 signaling pathway, and the apoptosis of neuronal cells, thereby exerting the neuroprotective effect.

RF09 | PSUN29 Evidence for a Founder Effect of SDHB Exon 1 Complete Deletion in Brazilian Patients with Paraganglioma

Abstract Background Pheochromocytomas and paragangliomas (PPGLs) have the highest degree of heritability among endocrine tumors. Currently, ∼40% of PPGL individuals have a genetic germline pathogenic variant and exist at least 12 different genetic syndromes related to these tumors. Pathogenic variants in the Succinate Dehydrogenase Complex Subunit B (SDHB) gene account for about 10% of PPGL cases. Moreover, SDHB pathogenic variants are the most well-established risk factor to predict metastatic disease (40%-50% of cases). Germline SDHB large deletions are very rare worldwide, but SDHB exon 1 deletion has been reported in patients with PPGLs from Portugal and Spain. Indeed, a putative founder effect for SDHB exon 1 deletion was suggested in PPGL patients from Iberian Peninsula. Aim To investigate a putative founder effect for SDHB exon 1 deletion. Methods Eighteen unrelated Brazilian patients with germline heterozygous SDHB pathogenic variants were included. Additionally, two unrelated individuals with SDHB exon 1 complete deletion from Argentina were studied. SDHB pathogenic variants were investigated by automated SAGER sequencing, multiplex ligation-dependent probe amplification (SALSA MLPA Probemix P226 SDH) and/or high-throughput sequencing. Five SDHB flanking microsatellite markers at chromosome 1p (D1S2697, GATA29A05, D1S2826, D1S2644, and D1S199) were used to investigate if patients carrying this deletion have a common origin. Haplotypes were reconstructed using the PHASE algorithm (v. 2.1). A control group comprising 26 unrelated Brazilian individuals was also studied. Results Among 18 Brazilian patients with germline SDHB pathogenic variants, heterozygous SDHB exon 1 complete deletion was identified in 6 of them (33% of the cases). The remaining 12 patients presented intragenic SDHB pathogenic variants without hotspot location. All Brazilian index patients with SDHB exon 1 deletion presented with paraganglioma, located mostly in the abdomen (4 abdominal; one thoracic; two head and neck and one colonic). Median age was 31.5 years and metastatic disease occurred in 3 (50%) of them. Haplotype analysis showed that 4 apparently unrelated Brazilian patients (4 out of 6 cases, 67%) shared a common allele (SDHB-GATA29A05-D1S2826-D1S2644-D1S199 | SDHB-186-130-213-102), which was not seen in chromosomes without the SDHB exon 1 deletion (p= 0.01). The two cases from Argentina did not have this haplotype, suggesting that SDHB exon 1 deletion in Argentina have a different origin. Conclusion SDHB exon 1 complete deletion was the most frequent SDHB defect in our cohort. Our findings indicate a founder effect for SDHB exon 1 complete deletion in Brazilian patients with paraganglioma. Support: Sao Paulo Research Foundation (FAPESP) grant 2019/15873-6 Presentation: Saturday, June 11, 2022 1:24 p.m. - 1:29 p.m., Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.

Blood Neuroexosomal Mitochondrial Proteins Predict Alzheimer Disease in Diabetes.

There is accumulating evidence that mitochondrial dysfunction is associated with the contribution of diabetes to Alzheimer disease (AD) progression. Neuronal mitochondrial proteins are found in plasma neuronal-derived exosomes (NDEs) at levels that reflect those in brain neurons. Here, we tested the performance of mitochondrial proteins in plasma NDEs to predict cognitive decline and brain injury in participants with diabetes. The study participants with type 2 diabetes mellitus (T2DM) included 41 cognitively normal control subjects, 97 individuals with mild cognitive impairment (MCI) (68 individuals with stable MCI; 29 individuals with progressive MCI), and 36 patients with AD dementia. Plasma neuroexosomal proteins were measured by ELISA kits. Spearman correlation was used to test associations between plasma neuroexosomal mitochondrial proteins and other core biomarkers of AD. Diagnostic accuracy for progressive MCI and AD was obtained for mitochondrial proteins using receiver operating characteristic curve analyses. The associations of mitochondrial proteins with the conversion from MCI to AD were assessed by Cox proportional hazard regression analysis. Plasma levels of neuroexosomal NADH ubiquinone oxidoreductase core subunit S3 (NDUFS3) and succinate dehydrogenase complex subunit B (SDHB) were significantly lower in patients with T2DM with AD dementia and progressive MCI than in cognitively normal subjects (P < 0.001 for both groups). We also found that plasma neuroexosomal NDUFS3 and SDHB levels were lower in progressive MCI subjects than in stable MCI subjects. Both plasma neuroexosomal NDUFS3 and SDHB offer diagnostic utility for AD. Low plasma neuroexosomal SDHB levels significantly predicted conversion from MCI to AD. In addition, low mitochondrial protein levels were associated with the rate of hippocampal and gray matter atrophy and reduced AD signature cortical thickness in progressive MCI over the follow-up period. These data suggest that both plasma neuroexosomal NDUFS3 and SDHB are already increased at the early clinical stage of AD, and indicate the promise of plasma neuroexosomal mitochondrial proteins as diagnostic and prognostic biomarkers for the earliest symptomatic stage of AD in participants with diabetes.

Colorectal paragangliomas with immunohistochemical deficiency of succinate dehydrogenase subunit B.

Recent progress in paraganglioma (PGL) revealed genotype-phenotype relationship, especially succinate dehydrogenase complex subunit B (SDHB) gene mutation-related to the extra-adrenal origin and metastasis. SDHB-immunohistochemistry can detect all types of SDH-subunit mutations, and is a useful tool to detect SDH-mutation tumors. PGLs usually occur along with sympathetic, and parasympathetic chains, however, colorectal paraganglioma is extremely rare. We have experienced one sigmoid colon PGL and one rectal PGL. These colorectal PGLs: a sigmoid colon PGL measuring 25 mm associated with a gastrointestinal stromal tumor (GIST) of the stomach, and a rectal PGL measuring 75 × 45 mm with elevated norepinephrine level were analyzed by immunohistochemistry for INSM1, chromogranin A, synaptophysin, tyrosine hydroxylase, dopamine-beta-hydroxylase, and SDHB and SDHA. The tumors were strongly positive for above markers, however, negative for SDHB. Both PGLs negative for SDHB immunohistochemistry were defined SDHB-deficient PGLs. Histologic grading of the PGLs by GAPP was well differentiated in sigmoid PGL versus poorly differentiated in rectal PGL. Although these PGLs were the same Stage II of TNM classification, the patient with sigmoid colon PGL had neither recurrence nor metastasis for 5 years after the operation, however, the patient with rectal PGL suffered the recurrent multiple metastases and expired 5 years after the operation. Herein, we compared these colorectal PGLs in regard to the patients' prognostic factors. Patient prognosis with these colorectal PGLs was mostly related to the tumor size and histologic grade under the same situation of SDH-deficiency.

Trimethylamine N-oxide promotes apoE-/- mice atherosclerosis by inducing vascular endothelial cell pyroptosis via the SDHB/ROS pathway.

Trimethylamine N-oxide (TMAO) is produced from the phosphatidylcholine metabolism of gut flora and acts as a risk factor of cardiovascular disease. However, the underlying mechanisms for its proatherogenic action remain unclear. This study aimed to observe the effect of TMAO on endothelial cell pyroptosis and explore the underlying mechanisms. Our results showed that TMAO promoted the progression of atherosclerotic lesions in apolipoprotein E-deficient (apoE-/- ) mice fed a high-fat diet. Pyroptosis and succinate dehydrogenase complex subunit B (SDHB) upregulation were detected in the vascular endothelial cells of apoE-/- mice and in cultured human umbilical vein endothelial cells (HUVECs) treated with TMAO. Overexpression of SDHB in HUVECs enhanced pyroptosis and impaired mitochondria and high reactive oxygen species (ROS) level. Pyroptosis in the SDHB overexpression of endothelial cells was inhibited by the ROS scavenger NAC. In summary, TMAO promotes vascular endothelial cell pyroptosis via ROS induced through SDHB upregulation, thereby contributing to the progression of atherosclerotic lesions.

Evaluation and validation of experimental condition-specific reference genes for normalization of gene expression in Asia II-I Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae)

Functional genomics in whitefly, Bemisia tabaci is gaining impetus due to its polyphagous nature, worldwide distribution and recently sequenced whole genome. These studies require an in-depth evaluation and validation of reference genes in different development stages and variable experimental setups. Normalization with reference genes is an essential step in the gene expression studies. Rather than selecting a reference gene empirically, the suitability of these genes must be validated for an individual organism, its specific stage or even for particular experimental conditions. The Quantitative real-time polymerase chain reaction (RT-qPCR) has evolved as an efficient and widely used technique for precise monitoring of gene expression. The prime focus of this study was to identify candidate reference genes in different developmental stages (adults, nymphs, eggs), sex (male and female), hosts (Gossypium hirsutum, G. arboreum), and under insecticidal and starvation stress. Expression stability of these genes in different experimental samples was evaluated by employing five different computational algorithms such as NormFinder, BestKeeper, Comparative delta-CT, geNorm and RefFinder. Our results identified a different set of reference genes under each experimental setup such as electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO), ubiquitin (UBIQ) and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) as best reference genes in adult whitefly. In addition, glutathione S-transferase (GST) in eggs, cyclophilin (CYCLOPH) in red eyed nymph, GAPDH in third instar, tubulin (Tub) in female, ubiquitin ribosomal protein S27 (UBIRPS2) in male, succinate dehydrogenase complex subunit B (SDHB) under insecticidal stress, ETF-QO under starvation stress, UBIRPS2 under host influence were the top most stable genes. Our studies report the importance of selection of specific reference genes for accurate gene expression studies under various experimental setups in B. tabaci.

MicroRNA-210 May Be a Preoperative Biomarker of Malignant Pheochromocytomas and Paragangliomas

BackgroundCurrently, no reliable predictive clinical or laboratory tests exist that can accurately distinguish between benign and malignant pheochromocytomas or paragangliomas (PPGLs). The aim of this study was to investigate if serum microRNA-210 (miR-210) levels could be a marker of malignancy in patients with PPGLs. MethodsPreoperative serum from patients with PPGLs was collected on the day of surgery. Clinical demographics, germline mutation status, primary tumor size, postoperative biochemical response, and the development of malignant disease were prospectively collected. Total microRNA was extracted from preoperative serum samples, and miR-210 levels were measured by quantitative real-time reverse transcription-polymerase chain reaction and normalized to miR-16. Prognostic variables were compared using univariable and multivariable analyses. ResultsOf the 35 patients, 10 (29%) were diagnosed with malignant PPGLs and 25 patients (71%) were diagnosed with benign PPGLs (median follow-up 72.5 mo). Sixty-nine percent of patients had a pheochromocytoma (n = 24/35) compared with 31% of patients with paraganglioma (n = 11/35). The most common germline mutation was succinate dehydrogenase complex subunit B (SDHB) (n = 10). On univariable analysis, lower serum miR-210 expression level (2.3 ± 0.5 versus 3.1 ± 1.2, P = 0.013) and larger primary tumor size (6.7 ± 5.0 cm versus 4.1 ± 2.3 cm, P = 0.043) were significantly associated with malignant disease. No significant prognostic variables were found on multivariable analysis. ConclusionsIn this pilot study, low serum miR-210 expression levels and large primary tumors were identified to be markers of PPGL malignancy on univariable analysis. Given the initial encouraging results in a small cohort, further investigation is warranted to determine if serum miR-210 levels are prognostic.

Continued Tumor Reduction of Metastatic Pheochromocytoma/Paraganglioma Harboring Succinate Dehydrogenase Subunit B Mutations with Cyclical Chemotherapy.

Patients harboring germline mutations in the succinate dehydrogenase complex subunit B (SDHB) gene present with pheochromocytomas and paragangliomas (PPGL) that are more likely malignant and clinically aggressive. The combination chemotherapy cyclophosphamide, vincristine, and dacarbazine (CVD) was retrospectively evaluated in patients with SDHB-associated metastatic PPGL.Query Twelve metastatic PPGL patients harboring SDHB mutations/polymorphisms with undetectable SDHB immunostaining were treated with CVD. CVD therapy consisted of 750mg/m2 cyclophosphamide with 1.4mg/m2 vincristine on day1 and 600mg/m2 dacarbazine on days1 and 2, every 21-28days. Treatment outcome was determined by RECIST criteria as well as determination of response duration and progression-free and overall survivals. A median of 20.5 cycles (range 4-41) was administered. All patients had tumor reduction (12-100% by RECIST). Complete response was seen in two patients, while partial response was observed in 8. The median number of cycles to response was 5.5. Median duration of response was 478days, with progression-free and overall survivals of 930 and 1190days, respectively. Serial [18F]-fluorodeoxyglucose positron emission tomography and computed tomography imaging demonstrated continued incremental reduction in maximal standardized uptake values (SUVmax) values in 26/30 lesions. During treatment administration, the median SUV decreased from >25 to <6, indicating the efficacy of chemotherapy over a prolonged period of time. Prolonged therapy results in continued incremental tumor reduction, and is consistent with persistent drug sensitivity. CVD chemotherapy is recommended to be considered part of the initial management in patients with metastatic SDHB-related PPGL.

MP12-01 SYSTEMATIC GENETIC SCREENING IN A PROSPECTIVE GROUP OF DANISH PATIENTS WITH PHEOCHROMOCYTOMA

You have accessJournal of UrologyAdrenal1 Apr 2016MP12-01 SYSTEMATIC GENETIC SCREENING IN A PROSPECTIVE GROUP OF DANISH PATIENTS WITH PHEOCHROMOCYTOMA Morten Steen Svarer Hansen, Niels Jacobsen, Anja L Frederiksen, Lars Lund, Marianne S Andersen, and Dorte Glintborg Morten Steen Svarer HansenMorten Steen Svarer Hansen More articles by this author , Niels JacobsenNiels Jacobsen More articles by this author , Anja L FrederiksenAnja L Frederiksen More articles by this author , Lars LundLars Lund More articles by this author , Marianne S AndersenMarianne S Andersen More articles by this author , and Dorte GlintborgDorte Glintborg More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2016.02.2441AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Recent guidelines recommend consideration of genetic screening in all newly diagnosed patients with pheochromocytoma. We wanted to evaluate results of systematic genetic screening in patients newly diagnosed with pheochromocytoma. METHODS All patients diagnosed with pheochromocytoma in the Region of Southern Denmark during 2006-2013 without previously recognized monogenetic aetiology were offered genetic screening for mutations in the genes von Hippel-Lindau tumor suppressor gene (VHL), rearranged during transfection protooncegene (RET), succinate dehydrogenase complex, subunit B (SDHB), SDH subunit C (SDHC) and SDH subunit D (SDHD). Systematic clinical and biochemical evaluation were performed in all patients. RESULTS Forty-one patients were included in the study and genetic data were available in 35/41 patients. Four patients had known monogenetic aetiology prior to the diagnosis of pheochromocytoma (VHL, n=2, neurofibromatosis type 1, n=2). These patients were all younger than 45 years of age at time of diagnosis of pheochromocytoma (ages: 12, 33, 34 and 43 years), 2/4 patients had bilateral tumors and one patient had positive family history of pheochromocytoma. Genetic screening did not identify any mutations in patients with sporadic pheochromocytoma (n=31). Patients with sporadic pheochromocytoma had a median age of 58 years (range 33-80 years), 3/31 patients had bilateral tumors, one patient had multiple tumors and no patients had positive family history of pheochromocytoma. Twenty-four (68.6%) patients were diagnosed with pheochromocytoma due to evaluation of adrenal incidentaloma. CONCLUSIONS Monogenetic aetiology was found in 4/35 (11.4 %) patients with pheochromocytoma. Systematic genetic screening did not identify additional mutations in patients newly diagnosed with pheochromocytoma. © 2016FiguresReferencesRelatedDetails Volume 195Issue 4SApril 2016Page: e125 Advertisement Copyright & Permissions© 2016MetricsAuthor Information Morten Steen Svarer Hansen More articles by this author Niels Jacobsen More articles by this author Anja L Frederiksen More articles by this author Lars Lund More articles by this author Marianne S Andersen More articles by this author Dorte Glintborg More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Metastatic pheochromocytoma and paraganglioma.

Metastatic pheochromocytomas (PCs) and paragangliomas (PGLs) are rare neuroendocrine tumours with a strong genetic background. We searched the PubMed database through February 2015 to identify studies characterizing metastatic PCs/PGLs as well as currently established and evolving therapies. Large size tumours (> 5 cm), PASS score > 6 and Ki-67 labelling index > 3% are the most robust indices of metastatic PCs/PGLs albeit with great variability. Germline succinate dehydrogenase complex, subunit B (SDHB) mutation constitutes the main reliable molecular predictor of malignancy. Plasma and urinary methoxytyramine are the biochemical markers characterizing metastatic PCs/PGLs along with evolving molecular markers such as miRNAs and SNAIL. Conventional imaging is used for tumour localization, whereas (18)F-FDG-PET for staging of metastatic PCs/PGLs especially those related to SDHB gene mutations. In addition, (68)Ga-DOTATATE PET/CT is emerging as a highly sensitive alternative. Surgery remains the gold standard treatment in reducing tumour bulk and/or controlling the clinical syndrome. Treatment with (131)I-MIBG or radiolabelled somatostatin analogues is considered for unresectable disease. Conventional chemotherapy is reserved for more advanced and refractory to other therapies disease although new schemes are currently evolving. Recent genetic studies have highlighted a number of pathways involved in PCs/PGLs pathogenesis directing towards the use of targeted therapies which have still to be validated in clinical practice. Metastatic PCs/PGLs remain an orphan disease that is only curable by surgery. However, advances in genomic analyses have improved the pathogenesis of these tumours and may lead to effective and more personalized treatments in the near future.

Thyroid Paraganglioma.

Thyroid paragangliomas are rare tumors that arise from the inferior laryngeal paraganglia. Most patients are female and present with an asymptomatic thyroid nodule. Histologically, the tumor is composed of cells arranged in a well-defined nest (zellballen) pattern surrounded by a thin fibrovascular stroma. It is a diagnostic pitfall and is occasionally misdiagnosed as follicular neoplasm, medullary thyroid carcinoma, intrathyroid parathyroid proliferation, and especially secondary neuroendocrine tumors. Immunohistochemical stains (cytokeratin, parathyroid hormone, thyroid transcription factor 1, tyrosine hydroxylase, chromogranin A, synaptophysin, S100, calcitonin, carcinoembryonic antigen) are essential in establishing the diagnosis. Loss of succinate dehydrogenase complex, subunit B (SDHB), immunoexpression can be used to triage genetic testing because some mutations are associated with a higher risk for developing metastasis. Total thyroidectomy or lobectomy for solitary lesion is the preferred treatment. Elective lymph node dissection is usually not indicated. Postoperatively, patients should receive hormonal evaluation for functional disease and imaging for evaluation of multifocal or metastatic disease.

A case report and review of oncocytic variant of papillary thyroid carcinoma

Aim To present a case of oncocytic variant of papillary thyroid carcinoma and review the literature on this uncommon variant. Case report A 60-year-old male underwent a total thyroidectomy and right cervical level six lymph node dissection for a suspected papillary thyroid carcinoma based on FNA. The thyroid gland contained two nodules in the right lobe, 10 mm and 23 mm, both with a tan lobulated cut surface. Histologically, the smaller nodule was an adenomatoid nodule and the larger was an oncocytic variant of papillary thyroid carcinoma. The carcinoma cells possessed classic oncocytic morphology, positivity for succinate dehydrogenase complex subunit B (SDHB) and the characteristic nuclear features of papillary thyroid carcinoma – enlarged nuclei with pale chromatin, nuclear membrane grooves and irregularities, and intranuclear pseudoinclusions. Somewhat unusually, the cells were negative for Galectin-3 and HBME-1. There was lymphovascular invasion and three lymph node metastases were found. Discussion The oncocytic variant of papillary thyroid carcinoma can provide a diagnostic challenge, with possible differentials including oncocytic variants of follicular adenoma and carcinoma, medullary thyroid carcinoma and hyalinising trabecular tumour. With varying reports on its immunohistochemical profile, the nuclear features of papillary thyroid carcinoma remain the most useful diagnostic criteria for this tumour.

G103(P) An Interesting Case of Two Siblings With SDHB Mutations

Phaeochromocytoma presenting in childhood is rare.1 It commonly presents with the effects of catecholamine excess, the most consistent of which is hypertension.2 3 Patients with phaeochromocytoma presenting in childhood often...

Succinate dehydrogenase-deficient GISTs are characterized by IGF1R overexpression

Succinate dehydrogenase-deficient gastrointestinal stromal tumors (GISTs) demonstrate unique pathological and clinical features, including the absence of activating mutations of KIT and PDGFRA, and primary resistance to imatinib. They arise exclusively in the stomach and account for 5–7.5% of all adult stomach GISTs and the great majority of these tumors in childhood. Insulin-like growth factor 1 receptor (IGF1R) overexpression has been associated with wild-type and pediatric GISTs. We propose that IGF1R overexpression is a feature of succinate dehydrogenase-deficient GISTs as a group. We assessed succinate dehydrogenase complex subunit B (SDHB) and IGF1R expression by immunohistochemistry in eight known succinate dehydrogenase-deficient GISTs, three GISTs arising in the setting of neurofibromatosis type 1 syndrome and 40 unselected GISTs. Selected KIT and PDGFRA exons were amplified and sequenced from formalin-fixed paraffin-embedded tumor samples. All eight succinate dehydrogenase-deficient tumors were wild-type for KIT and PDGFRA, succinate dehydrogenase B negative and demonstrated IGF1R overexpression. The three neurofibromatosis-related tumors were succinate dehydrogenase B positive and IGF1R negative. Of the 40 unselected upper GISTs, five were wild-type for KIT and PDGFRA in the selected exons. Two of the wild-type GISTs were succinate dehydrogenase B negative and showed IGF1R overexpression and three were succinate dehydrogenase B positive and IGF1R negative. We conclude that IGF1R overexpression is a feature of succinate dehydrogenase deficient GIST as a group, rather than pediatric or wild-type GIST per se. Therefore, IGF1R inhibition represents a potential rational therapeutic approach in this recently recognized subgroup of GIST.

When is a phaeo not a phaeo? Depression in an adolescent leading to a phaeochromocytoma‐like biochemical profile

A previously healthy 14 4/12 year old boy presented with a 6 months history of a 10 kg weight loss, profuse sweating, fatigue, myalgia, sleep difficulties and loss of appetite. Other history was notable for ongoing feelings of sadness and anxiety, and three suicide attempts. On physical examination he was alert and oriented, his weight was 38.5 kg and his height 172 cm. The BMI SDS was −4.7. Blood pressure was 120/80 mm Hg and resting pulse was 130 bpm. He was sweating profusely, did not maintain eye contact, and was shivering. The remainder of his examination, including neurological was unremarkable. Diagnostic workup ruled out infectious and malignant causes. Thyroid function tests showed an increased fT4 level of 34.5 pmol/L (10–23), and a TSH level which was initially slightly low at 0.06 mIU/L (0.5–5.0), both of which normalized spontaneously in follow up tests. Medical psychiatry was also involved and provided supportive therapy and medication management. The sweating and resting tachycardia of 130 bpm prompted his primary team to perform an evaluation for pheochromocytoma with concerning results: his 24-hour urine collection revealed elevated dopamine and norepinephrine levels (Table 1). Table 1 Biochemical profile and clonidine suppression test results, and list of imaging studies performed To confirm the urinary catecholamine results and to localize the presumptive tumor, an extensive workup was carried out over the course of 1.5 years. Testing revealed a persistent elevation of urine catecholamines but negative anatomical and functional imaging studies (Table 1). In an effort to differentiate a true pheochromocytoma from a false positive elevation of catecholamines, a clonidine suppression test was carried out, which is reported to have 98%–100% specificity for pheochromocytoma, when positive.1 Our patient’s plasma normetanephrine and norepinephrine levels did not suppress sufficiently during the test, which was consistent with the presence of pheochromocytoma. During this test and the initial workup, the patient was not consuming any drugs or medication. Follow up imaging studies were carried out over the next 12 months and were still negative (Table 1). Genetic testing for pheochromocytoma was also performed including examination for mutations in ret proto-oncogene (RET), succinate dehydrogenase complex, subunit B (SDHB), von Hippel-Lindau tumor suppressor gene (VHL), which were also negative. In parallel to the medical workup, he was followed by medical psychiatry for his depression, anxiety and physical complaints. Two months after his initial presentation, the antidepressant Citalopram was prescribed, but the patient was poorly adherent and did not take the medication. Treatment with Fluoxetine was initiated seven months post presentation, with better adherence, and titrated up to 30 mg daily. He also underwent occupational and physical therapy. This led to some improvement in his mood, anxiety, somatic complaints and functioning, and a concomitant, progressive drop in his catecholamine levels, which on last measurement had normalized (Table 1).

Mutation analysis of the SDHB and SDHD genes in pheochromocytomas and paragangliomas: identification of a novel nonsense mutation (Q168X) in the SDHB gene

Pheochromocytoma (PCC) and paraganglioma (PGL) are tumors of the autonomic nervous system. The former is a tumor that occurs in only adrenal glands, and the latter can be found in the head and neck or in the thorax and abdomen. In PCC and PGL, genetic mutations account for approximately 30% of functional (secrete catecholamines) and nonfunctional cases. In addition to RET, VHL and NF-1, genes encoding succinate dehydrogenase complex subunit B (SDHB), subunit C (SDHC), and subunit D (SDHD) are recognized as susceptibility genes for PCC and PGL. Recently, PCC and PGL caused by genetic mutations of SDHB, SDHC and SDHD were established as hereditary pheochromocytoma paraganglioma syndrome (HPPS). Approximately 15% of all PCCs and PGLs are recognized as HPPS. Among these three susceptibility genes, SDHB and SDHD are known to be strongly related to HPPS. The aim of this study was to analyze SDHB and SDHD mutations in PCC and PGL patients. Among 18 patients, we identified a novel heterozygous nonsense mutation at codon 168 resulting in a CAG (glutamine) to TAG (stop) substitution (Q168X) in the SDHB gene in a patient diagnosed with solitary sporadic PGL. A number of studies have reported that SDHB mutation-associated disease demonstrates a higher rate of malignancy. However, all seven patients diagnosed with malignancy in this study did not have genetic mutation of SDHB and only one patient with no malignant sign had genetic mutation of SDHB. Further accumulation of cases is necessary to confirm the association between SDHB mutation and malignant potential.

A reason to panic in pregnancy

An 18-year-old woman presented to us in June, 2004, at 27 weeks’ gestation with aproteinuric hypertension (178/111 mm Hg) and intermittent panic attacks (palpitations, left abdominal pain, and perspiration). 24-h urinary catecholamine excretion was >20 000 nmol. Ultrasonography showed a 6·9 cm × 3·6 cm × 4·6 cm structure obscuring the left adrenal gland. Haemodynamic stability was achieved with phenoxybenzamine and labetolol, for the presumptive diagnosis of phaeochromocytoma. A staging CT was undertaken before elective caesarean at 37 weeks’; a healthy infant was delivered. The tumour was resected a month later. Histologically the tumour arose from the sympathetic paraganglion cells; the left adrenal gland itself was normal. Some vascular invasion was noted. DNA analysis showed VHL and RET genes to be normal, but there was a succinate dehydrogenase complex subunit B (SDH-B) gene mutation, predisposing her to paraganglioma syndrome type I. Postoperative ultrasound showed a 3·2 cm mass anterior to the inferior vena cava at the aortic bifurcation, but the patient declined further investigation. She remained asymptomatic until the 32nd week of her next pregnancy, when fl ushing and palpitations were associated with rising urinary catecholamine secretions (to 4423 nmol/day). MRI showed that the mass had grown slightly to 3·5 cm. Despite an asystolic episode during caesarean section at term, the patient survived to undergo laparoscopic resection of the tumour 6 weeks’ postpartum. Again, paraganglioma was identifi ed histologically. The patient remained asymptomatic at follow-up in April, 2009. Paragangliomas account for only 10–15% of catecholamine-secreting tumours. A large series put the prevalence of paraganglioma and phaeo chromocytoma during pregnancy at fi ve per million. Maternal and fetal mortality are 4% and 11%, respectively, which is related to delay in presentation and diagnosis. In pregnancy phaeochromocytomas may initially be missed, because the symptoms can mimic pre-eclampsia (table). Urinary catecholamine secretion and plasma metanephrines are not raised in normal pregnancy or pre-eclampsia and confi rm the diagnosis of phaeochromo cytoma. Adequate medical management is required before delivery and surgery. Inpatient observation and management are recommended because of the unpredictable nature of phaeochromocytoma in pregnancy, although successful outpatient management was achieved when our patient declined admission. Resection should promptly follow medical stabilisation in cases diagnosed prior to 24 weeks’; after this time maintenance medical therapy should continue to optimise fetal maturity. Elective caesarean allows close monitoring and is the preferred mode of delivery since labour can be lethal. Planned caesarean also off ers the opportunity for simultaneous tumour resection, but delaying this into the puerperium decreases vascularity and improves access. Germline mutations account for a quarter of phaeochromocytomas; commonly disease is of young onset and is multifocal or extra-adrenal. Associated familial syndromes including Von Recklinghausen’s disease, Von Hippel-Lindau disease, and multiple endocrine neoplasia types IIa and IIb. Mutations in SDH-B, SDH-C, and SDH-D genes account for 33% of patients with phaeochromocytoma due to genetic abnormalities. SDH genes code for discrete subunits of the mitochondrial enzyme complex II (involved in Kreb’s cycle) and act as classic tumour suppression genes. SDHB mutations are associated with a 33% risk of recurrence and malignancy, and SDH-D mutations with an increased risk of multifocal paragangliomas, and renal and thyroid carcinomas. In women of reproductive age, genetic testing for one of the familial syndromes associated with phaeochromocytoma should be considered when there is family history of an associated syndrome, if the patient has any clinical features associated with a syndrome, or if the woman has extra-adrenal or multifocal disease. Although, the penetrance of RET and VHL is understood, the proportion of women with SDH mutations who develop clinical disease is unknown, complicating genetic counselling. Women known to have syndromes associated with phaeochromocytomas should receive preconceptual counselling about risks of disease developing during pregnancy.

Specific electron transport chain abnormalities in amyotrophic lateral sclerosis

In an amyotrophic lateral sclerosis (ALS) patient who also had an IgA gammopathy, autopsy studies identified the IgA in the surviving motor neurons. Further, the IgA bound the surface of isolated bovine motor neurons and inhibited neuronal proliferation in culture. To determine the pathologic basis of this IgA interaction with motor neurons, a neuroblastoma cDNA library was generated and screened with the IgA monoclonal antibody. Reactive clones were identified as flavin adenine dinucleotide (FAD) synthetase. To extend this finding to ALS in general, quantitative RT-PCRs were performed on blood samples from 26 ALS and 30 control blood samples to determine mRNA expression levels of FAD synthetase and other electron transport chain proteins, specifically riboflavin kinase (RFK), cytochrome C1 (CYC1), and succinate dehydrogenase complex subunit B (SDHB). All expression levels were measured against a control enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Expression levels for a non-respiratory chain protein (beta-actin) were also measured. We found that FAD synthetase expression levels were decreased in ALS samples compared to expression levels in controls (P = 0.0151). Expression levels for RFK, CYC1, and SDHB were also significantly decreased in the ALS group (P = 0.0025, P = 0.0002, and P < 0.0001, respectively). As control, expression levels for beta-actin did not show a significant difference between ALS and control groups (P = 0.2118). Our data show that a reduction in electron transport proteins, namely FAD synthetase, RFK, CYC1, and SDHB, is seen in patients with ALS. It is possible that this may have an effect on oxygen-dependent metabolic pathways. Human motor neurons may be particularly susceptible to injury if there is sub-optimal oxidative metabolism.

Methylation of the p16INK4A promoter is associated with malignant behavior in abdominal extra-adrenal paragangliomas but not pheochromocytomas

Pheochromocytomas and abdominal extra-adrenal paragangliomas are related to endocrine tumors of the sympathetic nervous system. Studies in animal models have shown that inactivation of the products of the cyclin dependent kinase inhibitor 2A (CDKN2A) gene locus, p16INK4A and p14ARF, promotes the development of pheochromocytoma, especially in malignant form. The present study evaluated the involvement of CDKN2A in human pheochromocytomas and abdominal extra-adrenal paragangliomas from 55 patients. Promoter methylation was assessed using quantitative Pyrosequencing and methylation-specific PCR, and mRNA expression was measured by quantitative real-time PCR. For p16, western blot analysis and sequencing were also performed. succinate dehydrogenase complex subunit B (SDHB) sequencing analysis included extra-adrenal paragangliomas, all tumors classified as malignant, and cases diagnosed at 30 years or younger. The p16INK4A promoter was heavily methylated in a subset of paragangliomas, and this was significantly associated with malignancy (P<0.0043) and SDHB mutation (P<0.002). p16INK4A mRNA expression showed moderate suppression in malignant cases (P<0.05). In contrast, very little p14ARF promoter methylation was seen and there was no significant difference in p14ARF expression between tumors and normal samples. The p16 protein expression was reduced in 16 tumors, and sequence variations were observed in four tumors including the missense mutation A57V and the single nucleotide polymorphism (SNP) A148T. The results suggest that p16INK4A, and not p14ARF, is a subject of frequent involvement in these tumors. Importantly, hypermethylation of the p16INK4A promoter was significantly associated with malignancy and metastasis, and SDHB gene mutations. This finding suggests an etiological link and could provide a clinical utility for diagnostic purposes.

A Giant Cystic Pheochromocytoma of the Adrenal Gland

Adrenal pheochromocytomas are rare catecholamine-secreting tumors that originate from chromaffin cells in the adrenal medulla, and giant pheochromocytomas with cystic changes are particularly rare. We report a case of a 46-year-old man who presented with episodic hypertension and headache. Radiographic studies showed an 18-cm cystic mass in the left upper quadrant of the abdomen; further workups, which included light microscopy, immunohistochemical, and electron microscopic analysis, revealed a pheochromocytoma of the left adrenal gland. Cytogenetic analysis and genetic mutation analyses for von-Hippel-Lindau (VHL), rearranged during transfection (RET), and succinate dehydrogenase complex subunit B (SDHB) genes were also performed but failed to reveal any abnormalities within the tumor cells.