Gene Summary

Gene:SDHC; succinate dehydrogenase complex subunit C
Aliases: CYBL, PGL3, QPS1, SDH3, CYB560
Summary:This gene encodes one of four nuclear-encoded subunits that comprise succinate dehydrogenase, also known as mitochondrial complex II, a key enzyme complex of the tricarboxylic acid cycle and aerobic respiratory chains of mitochondria. The encoded protein is one of two integral membrane proteins that anchor other subunits of the complex, which form the catalytic core, to the inner mitochondrial membrane. There are several related pseudogenes for this gene on different chromosomes. Mutations in this gene have been associated with paragangliomas. Alternatively spliced transcript variants have been described. [provided by RefSeq, May 2013]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:succinate dehydrogenase cytochrome b560 subunit, mitochondrial
Source:NCBIAccessed: 01 September, 2019


What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 01 September 2019 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

Tag cloud generated 01 September, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (5)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: SDHC (cancer-related)

Lemelin A, Lapoirie M, Abeillon J, et al.
Pheochromocytoma, paragangliomas, and pituitary adenoma: An unusual association in a patient with an SDHD mutation. Case report.
Medicine (Baltimore). 2019; 98(30):e16594 [PubMed] Related Publications
RATIONALE: Pituitary adenomas and paragangliomas are both rare endocrine diseases. Paragangliomas (PGL)/pheochromocytomas (PHEO) are part of an inherited syndrome in about 30% to 40% of cases. Among familial cases, mutations of the succinate dehydrogenase (SDH) subunit genes (succinate dehydrogenase subunit [SDH]B, SDHC, SDHD, succinate dehydrogenase subunit AF2 [SDHAF2] , and SDHA) are the most common cause.
PATIENT CONCERNS: We here report a 31-year-old patient with a known SDHD mutation whose disease has been revealed by a left PHEO during childhood and who presented at age 29 years a large paraganglioma of the right jugular foramen, a concomitant PHEO of the left adrenal and 2 retroperitoneal paragangliomas. A pituitary incidentaloma was found during investigations on a fluorodeoxyglucose (FDG)-positron emission tomography (PET) (FDG-PET).
DIAGNOSIS: A pituitary magnetic resonance imaging (MRI) confirmed the presence of a 14 mm pituitary macroadenoma. The pituitary function was normal except for hypogonadotropic hypogonadism. On examination of the fundus, a diagnosis of Pseudo Foster-Kennedy syndrome was made due to a venous compression of the right jugular vein caused by the paraganglioma (PGL). The pituitary adenoma was not compressive to the optic chiasm.
INTERVENTIONS: A treatment with acetazolamide was started in order to improve intracranial hypertension. The patient couldn't benefit of a surgical approach for the paraganglioma of the right jugular foramen; the patient has been treated with stereotactic radiosurgery (Gamma Knife).
OUTCOMES: The most recent MRI revealed that the right jugular foramen PGL is stable and the latest visual assessment demonstrated stability despite a recent reduction in acetazolamide dosage. A surveillance by MRI of the pituitary adenoma has been planned.
LESSONS: The association of a pituitary adenoma to paragangliomas within a same patient is very uncommon and raises the question of related physiopathological mechanisms.

Zhong J, Pan R, Ying X, et al.
Significant association between KDM1A promoter hypomethylation and colorectal cancer in Han Chinese.
Pathol Res Pract. 2019; 215(3):532-538 [PubMed] Related Publications
Lysine-specific histone demethylase 1A gene (KDM1A) promotes tumorigenesis. The aim of this study was to investigate the association between KDM1A methylation and colorectal cancer (CRC). Currently, we collected 37 paired CRC tissues and adjacent non-tumor tissues from Jiangsu province and 75 paired CRC tissues and adjacent non-tumor tissues from Zhejiang province to conduct a two-stage experiment to study the association between KDM1A methylation and CRC. We used qMSP to measure the KDM1A promoter methylation, and the percentage of methylation reference (PMR) to quantify the KDM1A promoter methylation level. To investigate the effect of the selected KDM1A fragment on gene expression regulation, we also performed a dual luciferase reporter gene assay. In the stage I study, the KDM1A promoter methylation level in CRC tumor tissues was significantly lower than that in adjacent non-tumor tissues (median PMR: 6.93% vs 10.25%, P =  0.033). The results of the stage II study were similar to those of the stage I study (mean PMR: 12.94% versus 17.42%, P =  0.016). In addition, a clinical pathology subgroup analysis found that KDM1A hypomethylation was associated with CRC only in patients with well-differentiated CRC (stage I: P =  0.047; stage II: P =  0.040). The dual luciferase reporter assay showed that the transcriptional activity of the recombinant pGL3-KDM1A plasmid was significantly higher (fold change = 2, P =  0.0009). In conclusion, our results suggest that KDM1A hypomethylation is significantly associated with CRC.

Ding Y, Feng Y, Wells M, et al.
SDHx gene detection and clinical Phenotypic analysis of multiple paraganglioma in the head and neck.
Laryngoscope. 2019; 129(2):E67-E71 [PubMed] Related Publications
OBJECTIVES: The goal of this study was to detect and explore the mechanisms of the succinate dehydrogenase (SDH) complex subunit-related gene mutations in cases of multiple paraganglioma (PGL) in the head and neck.
METHODS: In Beijing Tongren Hospital (Capital Medical University, Beijing, People's Republic of China) between January 2013 and February 2017, 23 cases of head and neck multiple PGL were evaluated by genetic sequencing. From these cases, four hereditary families and 10 cases with sporadic occurrences were found. Gene mutations, including SDHD, SDHB, SDHC, SDHAF2, VHL and RET in germ cells and somatic cells, were detected by gene capture and high throughput sequencing.
RESULTS: In family 1, 12 instances of SDHD gene mutation were detected, eight of which manifested as bilateral carotid body tumor (CBT) with one bilateral malignant CBT. In family 2, three cases of SDHD mutation were found with one case of bilateral CBT and two cases of unilateral CBT. In family 3, two cases of SDHD gene mutation were found, both characterized by vagus PGL and pheochromocytoma. Of the 10 patients with sporadic manifestations, five cases of SDHD gene mutation and one case of RET gene mutation were detected. Two novel gene mutations, c.387_393del7 mutation of SDHD gene and c.3247A>G mutation of RET gene, were also detected.
CONCLUSION: In patients with multiple PGL in the head and neck, these are accompanied by a genetic mutation of the germ cell. In this case study, this mutation was most commonly a mutation of the SDHD gene.
LEVEL OF EVIDENCE: 4 Laryngoscope, 129:E67-E71, 2019.

Oudijk L, Gaal J, de Krijger RR
The Role of Immunohistochemistry and Molecular Analysis of Succinate Dehydrogenase in the Diagnosis of Endocrine and Non-Endocrine Tumors and Related Syndromes.
Endocr Pathol. 2019; 30(1):64-73 [PubMed] Related Publications
Succinate dehydrogenase (SDH) is an enzyme complex, composed of four protein subunits, that plays a role in both the citric acid cycle and the electron transport chain. The genes for SDHA, SDHB, SDHC, and SDHD are located in the nuclear DNA, and mutations in these genes have initially been described in paragangliomas (PGL) and pheochromocytomas (PCC), which are relatively rare tumors derived from the autonomic nervous system and the adrenal medulla, respectively. Patients with SDH mutations, that are almost exclusively in the germline, are frequently affected by multiple PGL and/or PCC. In addition, other tumors have been associated with SDH mutations as well, including gastrointestinal stromal tumors, SDH-deficient renal cell carcinoma, and pituitary adenomas. Immunohistochemistry for SDHB and SDHA has been shown to be a valuable additional tool in the histopathological analysis of these tumors, and can be considered as a surrogate marker for molecular analysis. In addition, SDHB immunohistochemistry is relevant in the decision-making whether a genetic sequence variant represents a pathogenic mutation or not. In this review, we highlight the current knowledge of the physiologic and pathologic role of the SDH enzyme complex and its involvement in endocrine and non-endocrine tumors, with an emphasis on the applicability of immunohistochemistry.

Wang G, Rao P
Succinate Dehydrogenase-Deficient Renal Cell Carcinoma: A Short Review.
Arch Pathol Lab Med. 2018; 142(10):1284-1288 [PubMed] Related Publications
Succinate dehydrogenase (SDH) is a mitochondrial enzyme complex composed of 4 protein subunits (SDHA, SDHB, SDHC, and SDHD). Germ line mutations of the genes encoding these SDH subunits result in hereditary syndromes harboring pheochromocytomas/paragangliomas, gastrointestinal stromal tumors, renal cell carcinomas, and pituitary adenomas. SDH-deficient renal cell carcinomas are rare, with a mean age of 38 to 40 years. Histologically, these tumors show a characteristic appearance that includes a solid, nested, or tubular architecture with variable cysts. Cells are typically cuboidal, have indistinct cell borders and eosinophilic cytoplasm, and show flocculent intracytoplasmic inclusions. Loss of immunohistochemical staining for SDHB is the hallmark of these tumors. Although most SDH-deficient renal cell carcinomas are clinically indolent, some tumors may behave aggressively, particularly those with a high nuclear grade, tumor necrosis, or sarcomatoid differentiation. Accurate classification of these tumors is important for clinical follow-up, screening, and genetic evaluation of the patients and other family members for this hereditary tumor syndrome.

Niu X, Gao Z, Qi S, et al.
Macropinocytosis activated by oncogenic Dbl enables specific targeted delivery of Tat/pDNA nano-complexes into ovarian cancer cells.
Int J Nanomedicine. 2018; 13:4895-4911 [PubMed] Free Access to Full Article Related Publications
Background: Successful implementation of gene therapy heavily relies on efficiently delivering genetic materials and specific targeting into cells. Oncogene-driven endocytosis stimulates nutrient uptake and also develops an endocytosis-mediated defense against therapeutic agents. Cell-penetrating peptides, typically HIV-Tat, are well known for efficient delivery of nucleic acid drugs but lack targeting specificity. Various passive targeting strategies were pursued to enhance the tumor targeting efficiency; however, they are still limited by complicated cellular endocytosis routes and the heterogeneity of cancer types.
Methods: Tat/pDNA complexes were noncovalently compacted and their physiochemical properties were determined. The siRNA pool and pLV-RNAi-GFP lentivirus were used to knock down
Results: pGL3 plasmid DNA was noncovalently compacted with the Tat peptide into nano-size complexes at high N/P ratios. Macropinocytosis, a clathrin- and caveolin-independent endocytosis process, was shown to contribute to the uptake of middle-sized (∼600 nm) Tat/pGL3 complexes. Cell-type-specific variation in macropinocytosis was essentially controlled by the action of the
Conclusion: Such an aspect can be exploited to selectively confer targeted delivery of Tat/pDNA nano-complexes into ovarian cancer cells. Our work provides a novel alternative for targeted delivery of cell-penetrating peptide-based nucleic acid drugs into certain tumor types if specific endocytosis pathways are used.

Liu X, Zhu C, Li J, et al.
HBV Upregulates CtBP2 Expression via the X Gene.
Biomed Res Int. 2018; 2018:6960573 [PubMed] Free Access to Full Article Related Publications
Background: Hepatitis B virus (HBV) infection causes acute and chronic liver diseases that can eventually develop into cirrhosis and hepatocellular carcinoma (HCC), but the carcinogenesis of HBV is not fully understood. Carboxyl-terminal-binding protein 2 (CtBP2) plays an important role in tumorigenesis and progression. The aim of this study was to investigate the effect of HBV on CtBP2 expression and to explore its mechanism.
Methods: Real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) and western blotting were used to evaluate the CtBP2 mRNA and protein expression levels in tissues and cells. The HBV infectious clone pHBV1.3 and plasmids expressing a single gene of the HBV genome were cotransfected with the CtBP2 gene promoter pGL3-CtBP2 into the human hepatoma cell line HepG2, and luciferase activity was determined using a luminometer.
Results: CtBP2 expression was higher in HBV-related HCC tissues than in paracancerous tissues. CtBP2 expression was higher in HepG2.2.15 cells integrated with the HBV genome than in HepG2 cells. pHBV1.3 upregulated CtBP2 mRNA and protein expression. The HBV X gene significantly activated CtBP2 gene promoter activity, and CtBP2 mRNA and protein expression were upregulated by the HBV X gene. This activation effect was enhanced by the increase in the dose of the X gene, showing metrological dependence.
Conclusion: HBV may be involved in the occurrence and development of HCC by upregulating CtBP2 expression.

Ong RKS, Flores SK, Reddick RL, et al.
A Unique Case of Metastatic, Functional, Hereditary Paraganglioma Associated With an SDHC Germline Mutation.
J Clin Endocrinol Metab. 2018; 103(8):2802-2806 [PubMed] Related Publications
Context: Mutations in genes encoding for the succinate dehydrogenase (SDH) complex are linked to hereditary paraganglioma syndromes. Paraganglioma syndrome 3 is associated with mutations in SDHC and typically manifests as benign, nonfunctional head and neck paragangliomas.
Design: We describe a case of a 51-year-old woman who initially presented with diarrhea and hypertension and was found to have a retroperitoneal mass, which was resected with a pathology consistent with paraganglioma. Five years later, her symptoms recurred, and she was found to have new retroperitoneal lymphadenopathy and lytic lesions in the first lumbar vertebral body and the right iliac crest, which were visualized on CT scan and octreoscan but not on iodine-123-meta-iodobenzylguanidine (123I-MIBG) and bone scans. She had significantly elevated 24-hour urine norepinephrine and dopamine. The patient received external beam radiation and a series of different antineoplastic agents. Her disease progressed, and she eventually expired within 2 years. Genetic testing revealed a heterozygous SDHC c.43C>T, p.Arg15X mutation, which was also detected in her daughter and her grandson, both of whom have no biochemical or imaging evidence of paraganglioma syndrome yet.
Conclusion: We report a unique case of functional, metastatic abdominal paraganglioma associated with SDHC germline mutation. Our case exemplifies that SDHC germline mutation has variable penetrance, which may manifest with an aggressive biology that could be missed by a 123I-MIBG scan.

Andrade MO, Cunha VSD, Oliveira DC, et al.
What determines mortality in malignant pheochromocytoma? - Report of a case with eighteen-year survival and review of the literature.
Arch Endocrinol Metab. 2018 Mar-Apr; 62(2):264-269 [PubMed] Related Publications
Pheochromocytoma (PCC) is a tumor derived from adrenomedullary chromaffin cells. Prognosis of malignant PCC is generally poor due to local recurrence or metastasis. We aim to report a case of malignant PCC with 18-year survival and discuss which factors may be related to mortality and long-term survival in malignant pheochromocytoma. The patient, a 45-year-old man, reported sustained arterial hypertension with paroxysmal episodes of tachycardia, associated with head and neck burning sensation, and hand and foot tremors. Diagnosis of PCC was established biochemically and a tumor with infiltration of renal parenchyma was resected. No genetic mutation or copy number variations were identified in SDHB, SDHD, SDHC, MAX and VHL. Over 18 years, tumor progression was managed with 131I-MIBG (iodine-metaiodobenzylguanidine) and 177Lutetium-octreotate therapy. Currently, the patient is asymptomatic and presents sustained stable disease, despite the presence of lung, para-aortic lymph nodes and femoral metastases. Adequate response to treatment with control of tumor progression, absence of significant cardiovascular events and other neoplasms, and lack of mutations in the main predisposing genes reported so far may be factors possibly associated with the prolonged survival in this case. Early diagnosis and life-long follow-up in patients with malignant pheochromocytoma are known to be crucial in improving survival.

Snezhkina AV, Lukyanova EN, Kalinin DV, et al.
Exome analysis of carotid body tumor.
BMC Med Genomics. 2018; 11(Suppl 1):17 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Carotid body tumor (CBT) is a form of head and neck paragangliomas (HNPGLs) arising at the bifurcation of carotid arteries. Paragangliomas are commonly associated with germline and somatic mutations involving at least one of more than thirty causative genes. However, the specific functionality of a number of these genes involved in the formation of paragangliomas has not yet been fully investigated.
METHODS: Exome library preparation was carried out using Nextera® Rapid Capture Exome Kit (Illumina, USA). Sequencing was performed on NextSeq 500 System (Illumina).
RESULTS: Exome analysis of 52 CBTs revealed potential driver mutations (PDMs) in 21 genes: ARNT, BAP1, BRAF, BRCA1, BRCA2, CDKN2A, CSDE1, FGFR3, IDH1, KIF1B, KMT2D, MEN1, RET, SDHA, SDHB, SDHC, SDHD, SETD2, TP53BP1, TP53BP2, and TP53I13. In many samples, more than one PDM was identified. There are also 41% of samples in which we did not identify any PDM; in these cases, the formation of CBT was probably caused by the cumulative effect of several not highly pathogenic mutations. Estimation of average mutation load demonstrated 6-8 mutations per megabase (Mb). Genes with the highest mutation rate were identified.
CONCLUSIONS: Exome analysis of 52 CBTs for the first time revealed the average mutation load for these tumors and also identified potential driver mutations as well as their frequencies and co-occurrence with the other PDMs.

Pathak BR, Breed AA, Deshmukh P, Mahale SD
Androgen receptor mediated epigenetic regulation of CRISP3 promoter in prostate cancer cells.
J Steroid Biochem Mol Biol. 2018; 181:20-27 [PubMed] Related Publications
Cysteine-rich secretory protein 3 (CRISP3) is one of the most upregulated genes in prostate cancer. Androgen receptor (AR) plays an important role not only in initial stages of prostate cancer development but also in the advanced stage of castration-resistant prostate cancer (CRPC). Role of AR in regulation of CRISP3 expression is not yet known. In order to understand the regulation of CRISP3 expression, various overlapping fragments of CRISP3 promoter were cloned in pGL3 luciferase reporter vector. All constructs were transiently and stably transfected in PC3 (CRISP3 negative) and LNCaP (CRISP3 positive) cell lines and promoter activity was measured by luciferase assay. Promoter activity of LNCaP stable clones was significantly higher than PC3 stable clones. Further in CRISP3 negative PC3 and RWPE-1 cells, CRISP3 promoter was shown to be silenced by histone deacetylation. Treatment of LNCaP cells with DHT resulted in increase in levels of CRISP3 transcript and protein. AR dependency of CRISP3 promoter was also evaluated in LNCaP stable clones by luciferase assay. To provide molecular evidence of epigenetic regulation of CRISP3 promoter and its response to DHT, ChIP PCR was performed in PC3 and LNCaP cells. Our results demonstrate that CRISP3 expression in prostate cancer cells is androgen dependent and in AR positive cells, CRISP3 promoter is epigenetically regulated by AR.

Schaefer IM, Hornick JL, Bovée JVMG
The role of metabolic enzymes in mesenchymal tumors and tumor syndromes: genetics, pathology, and molecular mechanisms.
Lab Invest. 2018; 98(4):414-426 [PubMed] Related Publications
The discovery of mutations in genes encoding the metabolic enzymes isocitrate dehydrogenase (IDH), succinate dehydrogenase (SDH), and fumarate hydratase (FH) has expanded our understanding not only of altered metabolic pathways but also epigenetic dysregulation in cancer. IDH1/2 mutations occur in enchondromas and chondrosarcomas in patients with the non-hereditary enchondromatosis syndromes Ollier disease and Maffucci syndrome and in sporadic tumors. IDH1/2 mutations result in excess production of the oncometabolite (D)-2-hydroxyglutarate. In contrast, SDH and FH act as tumor suppressors and genomic inactivation results in succinate and fumarate accumulation, respectively. SDH deficiency may result from germline SDHA, SDHB, SDHC, or SDHD mutations and is found in autosomal-dominant familial paraganglioma/pheochromocytoma and Carney-Stratakis syndrome, describing the combination of paraganglioma and gastrointestinal stromal tumor (GIST). In contrast, patients with the non-hereditary Carney triad, including paraganglioma, GIST, and pulmonary chondroma, usually lack germline SDH mutations and instead show epigenetic SDH complex inactivation through SDHC promoter methylation. Inactivating FH germline mutations are found in patients with hereditary leiomyomatosis and renal cell cancer (HLRCC) syndrome comprising benign cutaneous/uterine leiomyomas and renal cell carcinoma. Mutant IDH, SDH, and FH share common inhibition of α-ketoglutarate-dependent oxygenases such as the TET family of 5-methylcytosine hydroxylases preventing DNA demethylation, and Jumonji domain histone demethylases increasing histone methylation, which together inhibit cell differentiation. Ongoing studies aim to better characterize these complex alterations in cancer, the different clinical phenotypes, and variable penetrance of inherited and sporadic cancer predisposition syndromes. A better understanding of the roles of metabolic enzymes in cancer may foster the development of therapies that specifically target functional alterations in tumor cells in the future. Here, the physiologic functions of these metabolic enzymes, the mutational spectrum, and associated functional alterations will be discussed, with a focus on mesenchymal tumor predisposition syndromes.

Zhan HQ, Li ST, Shu Y, et al.
Alpha gene upregulates TFEB expression in renal cell carcinoma with t(6;11) translocation, which promotes cell canceration.
Int J Oncol. 2018; 52(3):933-944 [PubMed] Related Publications
Renal cell carcinoma (RCC) with t(6;11) translocation has been characterized by the fusion of the Alpha gene with the TFEB gene. However, the underlying molecular mechanisms remain greatly uncharacterized and effective targeted therapy has yet to be identified. In this study, we examined the role of the Alpha gene in this tumor entity and the function of the fusion gene Alpha-TFEB product in vitro and in vivo. Our results revealed that the luciferase activity of Alpha1, Alpha2, Alpha3, Alpha4 and Alpha5 significantly increased compared with that of the pGL3-Basic group (P<0.01). The luciferase activity also increased significantly in the Alpha1, Alpha2 and Alpha5 groups compared with that of the normal TFEB gene group (P<0.01). In addition, the luciferase activity of Alpha5 was the strongest located in the 643-693 base sequence. The stable transfection of Alpha-TFEB into HK-2 and CaKi-2 cells promoted the expression of Alpha-TFEB mRNA and TFEB protein. Furthermore, the overexpression of TFEB increased cell proliferation and enhanced the cell invasive ability, and decreased cell apoptosis in the Alpha-TFEB stably transfected cells in vitro. In vivo experiments revealed that the overexpression of TFEB promoted tumorigenicity in nude mice, which was consistent with our in vitro results. On the whole, these data indicate that the overexpression of TFEB confers a potent oncogenic signal and may thus be a novel therapeutic target in RCC with t(6;11) translocation.

Turchini J, Cheung VKY, Tischler AS, et al.
Pathology and genetics of phaeochromocytoma and paraganglioma.
Histopathology. 2018; 72(1):97-105 [PubMed] Related Publications
Phaeochromocytoma and paraganglioma (PHEO/PGL) are rare tumours with an estimated annual incidence of 3 per million. Advances in molecular understanding have led to the recognition that at least 30-40% arise in the setting of hereditary disease. Germline mutations in the succinate dehydrogenase genes SDHA, SDHB, SDHC, SDHD and SDHAF2 are the most prevalent of the more than 19 hereditary genetic abnormalities which have been reported. It is therefore recommended that, depending on local resources and availability, at least some degree of genetic testing should be offered to all PHEO/PGL patients, including those with clinically sporadic disease. It is now accepted that that all PHEO/PGL have some metastatic potential; therefore, concepts of benign and malignant PHEO/PGL have no meaning and have been replaced by a risk stratification approach. Although there is broad acceptance that certain features, including high proliferative activity, invasive growth, increased cellularity, large tumour nests and comedonecrosis, are associated with an increased risk of metastasis, it remains difficult to predict the clinical behaviour of individual tumours and no single risk stratification scheme is endorsed or in widespread use. In this review, we provide an update on advances in the pathology and genetics of PHEO/PGL with an emphasis on the changes introduced in the WHO 2017 classification of endocrine neoplasia relevant to practising surgical pathologists.

Bernardo-Castiñeira C, Valdés N, Sierra MI, et al.
SDHC Promoter Methylation, a Novel Pathogenic Mechanism in Parasympathetic Paragangliomas.
J Clin Endocrinol Metab. 2018; 103(1):295-305 [PubMed] Related Publications
Context: Germline mutations in the succinate dehydrogenase A, B, C, and D genes (collectively, SDHx) predispose to the development of paragangliomas (PGLs) arising at the parasympathetic or sympathetic neuroendocrine systems. SDHx mutations cause absence of tumoral immunostaining for SDHB. However, negative SDHB immunostaining has also been found in a subset of PGLs that lack SDHx mutations.
Settings: Here, we report the comprehensive molecular characterization of one such a tumor of parasympathetic origin compared with healthy paraganglia and other PGLs with or without SDHx mutations.
Results: Integration of multiplatform data revealed somatic SDHC methylation and loss of the 1q23.3 region containing the SDHC gene. This correlated with decreased SDHC messenger RNA (mRNA) and protein levels. Furthermore, another genetic event found affected the VHL gene, which showed a decreased DNA copy number, associated with low VHL mRNA levels, and an absence of VHL protein detected by immunohistochemistry. In addition, the tumor displayed a pseudohypoxic phenotype consisting in overexpression of the hypoxia-inducible factor (HIF)-1α and miR-210, as well as downregulation of the iron-sulfur cluster assembly enzyme (ISCU) involved in SDHB maturation. This profile resembles that of SDHx- or VHL-mutated PGLs but not of PGLs with decreased VHL copy number, pointing to SDHC rather than VHL as the pathogenic driver.
Conclusions: Collectively, these findings demonstrate the potential importance of both the SDHC epigenomic event and the activation of the HIF-1α/miR-210/ISCU axis in the pathogenesis of SDHx wild-type/SDHB-negative PGLs. To our knowledge, this is the first case of a sporadic parasympathetic PGL that carries silencing of SDHC, fulfilling the two-hit Knudson's model for tumorigenesis.

Aldera AP, Govender D
Gene of the month: SDH.
J Clin Pathol. 2018; 71(2):95-97 [PubMed] Related Publications
Succinate dehydrogenase (SDH) is a heterotetrameric nuclear encoded mitochondrial protein complex which plays a role in the citric acid cycle and the electron transfer chain. Germline mutations in

Casey RT, Warren AY, Martin JE, et al.
Clinical and Molecular Features of Renal and Pheochromocytoma/Paraganglioma Tumor Association Syndrome (RAPTAS): Case Series and Literature Review.
J Clin Endocrinol Metab. 2017; 102(11):4013-4022 [PubMed] Free Access to Full Article Related Publications
Context: The co-occurrence of pheochromocytoma (PC) and renal tumors was linked to the inherited familial cancer syndrome von Hippel-Lindau (VHL) disease more than six decades ago. Subsequently, other shared genetic causes of predisposition to renal tumors and to PC, paraganglioma (PGL), or head and neck paraganglioma (HNPGL) have been described, but case series of non-VHL-related cases of renal tumor and pheochromocytoma/paraganglioma tumor association syndrome (RAPTAS) are rare.
Objective: To determine the clinical and molecular features of non-VHL RAPTAS by literature review and characterization of a case series.
Design: A review of the literature was performed and a retrospective study of referrals for investigation of genetic causes of RAPTAS.
Results: Literature review revealed evidence of an association, in addition to VHL disease, between germline mutations in SDHB, SDHC, SDHD, TMEM127, and MAX genes and RAPTAS [defined here as the co-occurrence of tumors from both classes (PC/PGL/HNPGL and renal tumors) in the same individual or in first-degree relatives]. In both the literature review and our case series of 22 probands with non-VHL RAPTAS, SDHB mutations were the most frequent cause of non-VHL RAPTAS. A genetic cause was identified in 36.3% (8/22) of kindreds.
Conclusion: Renal tumors and PC/PGL/HNPGL tumors share common molecular features and their co-occurrence in an individual or family should prompt genetic investigations. We report a case of MAX-associated renal cell carcinoma and confirm the role of TMEM127 mutations with renal cell carcinoma predisposition.

Bhowal A, Majumder S, Ghosh S, et al.
Pathway-based expression profiling of benign prostatic hyperplasia and prostate cancer delineates an immunophilin molecule associated with cancer progression.
Sci Rep. 2017; 7(1):9763 [PubMed] Free Access to Full Article Related Publications
Aberrant restoration of AR activity is linked with prostate tumor growth, therapeutic failures and development of castrate-resistant prostate cancer. Understanding the processes leading to AR-reactivation should provide the foundation for novel avenues of drug discovery. A differential gene expression study was conducted using biopsies from CaP and BPH patients to identify the components putatively responsible for reinstating AR activity in CaP. From the set of genes upregulated in CaP, FKBP52, an AR co-chaperone, was selected for further analysis. Expression of FKBP52 was positively correlated with that of c-Myc. The functional cross-talk between c-Myc and FKBP52 was established using c-Myc specific-siRNA to LNCaP cells that resulted in reduction of FKBP52. A non-canonical E-box sequence housing a putative c-Myc binding site was detected on the FKBP4 promoter using in silico search. LNCaP cells transfected with the FKBP52 promoter cloned in pGL3 basic showed increased luciferase activity which declined considerably when the promoter-construct was co-transfected with c-Myc specific-siRNA. ChIP-PCR confirmed the binding of c-Myc with the conserved E-box located in the FKBP52 promoter. c-Myc downregulation concomitantly affected expression of FGF8. Since expression of FGF8 is controlled by AR, our study unveiled a novel functional axis between c-Myc, AR and FGF8 operating through FKBP52.

Else T, Lerario AM, Everett J, et al.
Adrenocortical carcinoma and succinate dehydrogenase gene mutations: an observational case series.
Eur J Endocrinol. 2017; 177(5):439-444 [PubMed] Related Publications
OBJECTIVE: Germline loss-of-function mutations in succinate dehydrogenase (
PATIENTS AND RESULTS: We report four unrelated patients with ACC and
CONCLUSIONS: We observed truncating mutations in

Belinsky MG, Cai KQ, Zhou Y, et al.
Succinate dehydrogenase deficiency in a PDGFRA mutated GIST.
BMC Cancer. 2017; 17(1):512 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Most gastrointestinal stromal tumors (GISTs) harbor mutually exclusive gain of function mutations in the receptor tyrosine kinase (RTK) KIT (70-80%) or in the related receptor PDGFRA (~10%). These GISTs generally respond well to therapy with the RTK inhibitor imatinib mesylate (IM), although initial response is genotype-dependent. An alternate mechanism leading to GIST oncogenesis is deficiency in the succinate dehydrogenase (SDH) enzyme complex resulting from genetic or epigenetic inactivation of one of the four SDH subunit genes (SDHA, SDHB, SDHC, SDHD, collectively referred to as SDHX). SDH loss of function is generally seen only in GIST lacking RTK mutations, and SDH-deficient GIST respond poorly to imatinib therapy.
METHODS: Tumor and normal DNA from a GIST case carrying the IM-resistant PDGFRA D842V mutation was analyzed by whole exome sequencing (WES) to identify additional potential targets for therapy. The tumors analyzed were separate recurrences following progression on imatinib, sunitinib, and the experimental PDGFRA inhibitor crenolanib. Tumor sections from the GIST case and a panel of ~75 additional GISTs were subjected to immunohistochemistry (IHC) for the SDHB subunit.
RESULTS: Surprisingly, a somatic, loss of function mutation in exon 4 of the SDHB subunit gene (c.291_292delCT, p.I97Mfs*21) was identified in both tumors. Sanger sequencing confirmed the presence of this inactivating mutation, and IHC for the SDHB subunit demonstrated that these tumors were SDH-deficient. IHC for the SDHB subunit across a panel of ~75 GIST cases failed to detect SDH deficiency in other GISTs with RTK mutations.
CONCLUSIONS: This is the first reported case of a PDGFRA mutant GIST exhibiting SDH-deficiency. A brief discussion of the relevant GIST literature is included.

Settas N, Faucz FR, Stratakis CA
Succinate dehydrogenase (SDH) deficiency, Carney triad and the epigenome.
Mol Cell Endocrinol. 2018; 469:107-111 [PubMed] Free Access to Full Article Related Publications
In this report, we review the relationship between succinate dehydrogenase (SDH) deficiency and the epigenome, especially with regards to two clinical conditions. Carney triad (CT) is a very rare disease with synchronous or metachronous occurrence of at least three different tumor entities; gastric gastrointestinal stromal tumor (GIST), paraganglioma (PGL), and pulmonary chondroma. This condition affects mostly females and it is never inherited. Another disease that shares two of the tumor components of CT, namely GIST and PGL is the Carney-Stratakis syndrome (CSS) or dyad. CSS affects both genders during childhood and adolescence. We review herein the main clinical features and molecular mechanisms behind those two syndromes that share quite a bit of similarities, but one is non-hereditary (CT) whereas the other shows an autosomal-dominant, with incomplete penetrance, inheritance pattern (CSS). Both CT and CSS are caused by the deficiency of the succinate dehydrogenase (SDH) enzyme. The key difference between the two syndromes is the molecular mechanism that causes the SDH deficiency. Most cases of CT show down-regulation of SDH through site-specific hyper-methylation of the SDHC gene, whereas CSS cases carry inactivating germline mutations within one of the genes coding for the SDH subunits A, B, C, or D (SDHA, SDHB, SDHC, and SDHD). There is only partial overlap between the two conditions (there are a few patients with CT that have SDH subunit mutations) but both lead to increased methylation of the entire genome in the tumors associated with them. Other tumors (outside CT and CSS) that have SDH deficiency are associated with increased methylation of the entire genome, but only in CT there is site-specific methylation of the SDHC gene. These findings have implications for diagnostics and the treatment of patients with these, often metastatic tumors.

Yang D, Wang JJ, Li JS, Xu QY
miR-103 Functions as a Tumor Suppressor by Directly Targeting Programmed Cell Death 10 in NSCLC.
Oncol Res. 2018; 26(4):519-528 [PubMed] Related Publications
Non-small cell lung cancer (NSCLC) accounts for about 85% of all lung cancer cases. Absence of miR-103 has recently been identified to be associated with metastatic capacity of primary lung tumors. However, the exact role of miR-103 in NSCLC and the molecular mechanism are unclear. In the present study, we showed that miR-103 expression was reduced in NSCLC tissues and cells. miR-103 expression was negatively correlated with tumor size and stage. The overall survival was longer in patients with higher miR-103 level than in those with lower miR-103 expression. miR-103 inhibited cell proliferation in A549 cells, decreased tumor weight and volume, and prolonged survival of tumor-implanted nude mice. miR-103 increased apoptotic cell death in A549 cells. Furthermore, miR-103 decreased the invasion and migration abilities in A549 cells, as evidenced by Transwell and wound healing results. Downregulation of miR-103 significantly reduced the level of programmed cell death 10 (PDCD10). We found a significant decrease in the relative luciferase activity of the reporter gene in A549 cells cotransfected with the miR-103 mimic and pGL3-PDCD10 WT 3'-UTR, but not pGL3-PDCD10 mut 3'-UTR. We showed that overexpression of PDCD10 significantly inhibited miR-103-induced inhibition of cell proliferation, increased apoptosis, and decreased invasion and migration in A549 cells. Moreover, we found that PDCD10 expression was increased in NSCLC tissues and cells. PDCD10 expression was positively correlated with tumor size and stage. Overexpression of PDCD10 increased cell proliferation and inhibited apoptosis in A549 cells. The data demonstrated that dysregulation of the miR-103/PDCD10 signal may be a novel therapeutic target for the treatment of NSCLC.

Remacha L, Comino-Méndez I, Richter S, et al.
Targeted Exome Sequencing of Krebs Cycle Genes Reveals Candidate Cancer-Predisposing Mutations in Pheochromocytomas and Paragangliomas.
Clin Cancer Res. 2017; 23(20):6315-6324 [PubMed] Related Publications

Capasso M, McDaniel LD, Cimmino F, et al.
The functional variant rs34330 of CDKN1B is associated with risk of neuroblastoma.
J Cell Mol Med. 2017; 21(12):3224-3230 [PubMed] Free Access to Full Article Related Publications
The genetic aetiology of sporadic neuroblastoma is still largely unknown. We have identified diverse neuroblastoma susceptibility loci by genomewide association studies (GWASs); however, additional SNPs that likely contribute to neuroblastoma susceptibility prompted this investigation for identification of additional variants that are likely hidden among signals discarded by the multiple testing corrections used in the analysis of genomewide data. There is evidence suggesting the CDKN1B, coding for the cycle inhibitor p27Kip1, is involved in neuroblastoma. We thus assess whether genetic variants of CDKN1B are associated with neuroblastoma. We imputed all possible genotypes across CDKN1B locus on a discovery case series of 2101 neuroblastoma patients and 4202 genetically matched controls of European ancestry. The most significantly associated rs34330 was analysed in an independent Italian cohort of 311 cases and 709 controls. In vitro functional analysis was carried out in HEK293T and in neuroblastoma cell line SHEP-2, both transfected with pGL3-CDKN1B-CC or pGL3-CDKN1B-TT constructs. We identified an association of the rs34330 T allele (-79C/T) with the neuroblastoma risk (P

Rednam SP, Erez A, Druker H, et al.
Von Hippel-Lindau and Hereditary Pheochromocytoma/Paraganglioma Syndromes: Clinical Features, Genetics, and Surveillance Recommendations in Childhood.
Clin Cancer Res. 2017; 23(12):e68-e75 [PubMed] Related Publications
Von Hippel-Lindau disease (vHL) is a hereditary tumor predisposition syndrome that places affected individuals at risk for multiple tumors, which are predominantly benign and generally occur in the central nervous system or abdomen. Although the majority of tumors occur in adults, children and adolescents with the condition develop a significant proportion of vHL manifestations and are vulnerable to delayed tumor detection and their sequelae. Although multiple tumor screening paradigms are currently being utilized for patients with vHL, surveillance should be reassessed as the available relevant clinical information continues to expand. We propose a new vHL screening paradigm similar to existing approaches, with important modifications for some tumor types, placing an emphasis on risks in childhood. This includes advancement in the timing of surveillance initiation and increased frequency of screening evaluations. Another neuroendocrine-related familial condition is the rapidly expanding hereditary paraganglioma and pheochromocytoma syndrome (HPP). The tumor spectrum for patients with HPP syndrome includes paragangliomas, pheochromocytomas, renal cancer, and gastrointestinal stromal tumors. The majority of patients with HPP syndrome harbor an underlying variant in one of the

Tiwari A, Shah N, Sarathi V, et al.
Genetic status determines
J Med Imaging Radiat Oncol. 2017; 61(6):745-752 [PubMed] Related Publications
INTRODUCTION: Although few studies have demonstrated utility of
METHODS: The study was conducted at a tertiary health care centre. In addition to the routine investigations, all patients (n = 96) with PCC/PGL were evaluated with
RESULTS: The study included 96 patients with PCC/PGL(82 benign and 14 malignant). FDGSUVmax was significantly higher for malignant than benign PCC/PGL(P = 0.009) and for extra-adrenal PGL than adrenal PCC (P = 0.017). In subgroup analysis, metanephrine-secreting PCC and non-secretory PCC had significantly lower FDG SUVmax than normetanephrine-secreting PCC (P = 0.017, P = 0.038 respectively), normetanephrine-secreting-sympathetic PGL (P = 0.008, P = 0.019 respectively) and non-secretory sympathetic PGL (P = 0.003, P = 0.009 respectively). Patients with mutations in cluster 1 genes (n = 14) had significantly higher FDG SUVmax than those with mutations in cluster 2 genes (n = 4) (P = 0.04). Sensitivities of
CONCLUSION: The study suggests that the underlying genetic status determines FDG uptake in PCC/PGL and not location, secretory status or malignancy.

Wang X, Shojaie A, Zhang Y, et al.
Exploratory plasma proteomic analysis in a randomized crossover trial of aspirin among healthy men and women.
PLoS One. 2017; 12(5):e0178444 [PubMed] Free Access to Full Article Related Publications
Long-term use of aspirin is associated with lower risk of colorectal cancer and other cancers; however, the mechanism of chemopreventive effect of aspirin is not fully understood. Animal studies suggest that COX-2, NFκB signaling and Wnt/β-catenin pathways may play a role, but no clinical trials have systematically evaluated the biological response to aspirin in healthy humans. Using a high-density antibody array, we assessed the difference in plasma protein levels after 60 days of regular dose aspirin (325 mg/day) compared to placebo in a randomized double-blinded crossover trial of 44 healthy non-smoking men and women, aged 21-45 years. The plasma proteome was analyzed on an antibody microarray with ~3,300 full-length antibodies, printed in triplicate. Moderated paired t-tests were performed on individual antibodies, and gene-set analyses were performed based on KEGG and GO pathways. Among the 3,000 antibodies analyzed, statistically significant differences in plasma protein levels were observed for nine antibodies after adjusting for false discoveries (FDR adjusted p-value<0.1). The most significant protein was succinate dehydrogenase subunit C (SDHC), a key enzyme complex of the mitochondrial tricarboxylic acid (TCA) cycle. The other statistically significant proteins (NR2F1, MSI1, MYH1, FOXO1, KHDRBS3, NFKBIE, LYZ and IKZF1) are involved in multiple pathways, including DNA base-pair repair, inflammation and oncogenic pathways. None of the 258 KEGG and 1,139 GO pathways was found to be statistically significant after FDR adjustment. This study suggests several chemopreventive mechanisms of aspirin in humans, which have previously been reported to play a role in anti- or pro-carcinogenesis in cell systems; however, larger, confirmatory studies are needed.

Sbardella E, Cranston T, Isidori AM, et al.
Routine genetic screening with a multi-gene panel in patients with pheochromocytomas.
Endocrine. 2018; 59(1):175-182 [PubMed] Related Publications
PURPOSE: Several new gene mutations have been reported in recent years to be associated with a risk of familial pheochromocytoma. However, it is unclear as to whether extensive genetic testing is required in all patients.
METHODS: The clinical data of consecutive patients operated for pheochromocytoma over a decade in a tertiary referral center were reviewed. Genetic screening was performed using a 10-gene panel: RET, VHL, SDHB, SDHD, SDHA, SDHC, SDHAF2, MAX, TMEM127 and FH.
RESULTS: A total of 166 patients were analyzed: 87 of them had genetic screening performed (39 M: 44.8%, 48 F: 55.2%, age range 6-81 years, mean 45±16.8 years). In total, 22/87 (25.3%) patients had germline mutations, while 65/87 (74.7%) patients presented with apparently sporadic tumors. Germline VHL mutations were identified in 11.7% of patients, RET in 6.8% (five MEN2A/MEN2 and one MEN2B/MEN3), SDHD in 2.3%, MAX in 2.3%, SDHB in 1.1%, and TMEM127 in 1.1% of patients. At diagnosis, 15.1% of patients with unilateral non-syndromic pheochromocytoma showed germline mutations. We identified 19.7% of mutations in patients with unilateral-non-recurrent pheochromocytomas within 5 years vs. 50% in the recurrent-bilateral-metastatic group (p = 0.01). Germline mutations were more frequently seen with bilateral pheochromocytomas (p = 0.001): 80% of patients with bilateral disease had germline mutations (4 VHL, 3 RET, 1 MAX).
CONCLUSIONS: The advent of rapid genetic screening using a gene-panel makes it feasible to screen large cohorts of patients and provides a valuable tool to contribute to the prediction of bilateral and malignant disease and to screen family members.

Khadilkar K, Sarathi V, Kasaliwal R, et al.
Genotype-phenotype correlation in paediatric pheochromocytoma and paraganglioma: a single centre experience from India.
J Pediatr Endocrinol Metab. 2017; 30(5):575-581 [PubMed] Related Publications
BACKGROUND: Data on genotype-phenotype correlation in children is limited. Hence, we studied the prevalence of germline mutations and genotype-phenotype correlation in children with pheochromocytoma (PCC)/paraganglioma (PGL) and compared it with adult PCC/PGL cohort.
METHODS: A total of 121 consecutive, unrelated, index PCC/PGL patients underwent genetic testing for five PCC/PGL susceptibility genes (RET, VHL, SDHB, SDHD and SDHC) and were evaluated for clinical diagnosis of neurofibromatosis type1 (NF1).
RESULTS: Thirty patients (12 boys, 18 girls) presented at ≤20 years of age (mean age of 15.9±3.8 years). Children were more frequently symptomatic and more frequently had bilateral PCC than adults. Fourteen (46.7%) PCC/PGL children had germline mutations (VHL 10 [33.3%], SDHB 2 [6.6%], and SDHD 2 [6.6%]). Overall germline mutations (46.7% vs. 26.4%, p=0.04) and VHL mutations (33.3% vs. 10.9%, p=0.026) were significantly more common in children than in adults. In children with VHL mutations, bilateral PCC were more frequent than in adults with VHL mutations. Within the paediatric cohort, bilateral PCC (60% vs. 5%, p=0.002), PCC+sPGL (30% vs. 0%, p=0.03) and occurrence of a second PCC/PGL (30% vs. 0%, p=0.03) were significantly more frequent among children with VHL mutations than others.
CONCLUSIONS: All PCC/PGL children should be screened for germline mutations with first priority for VHL gene testing. Paediatric PCC/PGL patients with VHL mutations should be thoroughly evaluated for bilateral PCC and PCC+sPGL at initial presentation and closely followed up for occurrence of a second PCC/PGL.

De Sousa SMC, McCabe MJ, Wu K, et al.
Germline variants in familial pituitary tumour syndrome genes are common in young patients and families with additional endocrine tumours.
Eur J Endocrinol. 2017; 176(5):635-644 [PubMed] Related Publications
OBJECTIVE: Familial pituitary tumour syndromes (FPTS) account for 5% of pituitary adenomas. Multi-gene analysis via next-generation sequencing (NGS) may unveil greater prevalence and inform clinical care. We aimed to identify germline variants in selected patients with pituitary adenomas using a targeted NGS panel.
DESIGN: We undertook a nationwide cross-sectional study of patients with pituitary adenomas with onset ≤40 years of age and/or other personal/family history of endocrine neoplasia. A custom NGS panel was performed on germline DNA to interrogate eight FPTS genes. Genome data were analysed via a custom bioinformatic pipeline, and validation was performed by Sanger sequencing. Multiplex ligation-dependent probe amplification (MLPA) was performed in cases with heightened suspicion for
RESULTS: Forty-four patients with pituitary tumours, 14 of whom had a personal history of other endocrine tumours and/or a family history of pituitary or other endocrine tumours, were referred from endocrine tertiary-referral centres across Australia. Eleven patients (25%) had a rare variant across the eight FPTS genes tested:
CONCLUSIONS: A high yield of rare variants in genes implicated in FPTS can be found in selected patients using an NGS panel. It may also identify individuals harbouring more than one rare variant.

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