Targeting NRF2-Governed Glutathione Synthesis for SDHB-Mutated Pheochromocytoma and Paraganglioma.
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ABSTRACT:
SUBMITTER: Liu Y
PROVIDER: S-EPMC7072390 | biostudies-literature | 2020 Jan
REPOSITORIES: biostudies-literature
Publications
Targeting NRF2-Governed Glutathione Synthesis for <i>SDHB</i>-Mutated Pheochromocytoma and Paraganglioma.
Liu Yang Y Pang Ying Y Caisova Veronika V Ding Jianyi J Yu Di D Zhou Yiqiang Y Huynh Thanh-Truc TT Ghayee Hans H Pacak Karel K Yang Chunzhang C
Cancers 20200123 2
Succinate dehydrogenase subunit B (SDHB) deficiency frequently occurs in cluster I pheochromocytomas and paragangliomas (PCPGs). <i>SDHB</i>-mutated PCPGs are characterized by alterations in the electron transport chain, metabolic reprogramming of the tricarboxylic cycle, and elevated levels of reactive oxygen species (ROS). We discovered that <i>SDHB-</i>deficient PCPG cells exhibit increased oxidative stress burden, which leads to elevated demands for glutathione metabolism. Mechanistically, n ...[more]
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Project description:PurposePheochromocytomas and paragangliomas (PCPG) are usually benign neuroendocrine tumors. However, PCPGs with mutations in the succinate dehydrogenase B subunit (SDHB) have a poor prognosis and frequently develop metastatic lesions. SDHB-mutated PCPGs exhibit dysregulation in oxygen metabolic pathways, including pseudohypoxia and formation of reactive oxygen species, suggesting that targeting the redox balance pathway could be a potential therapeutic approach.Experimental designWe studied the genetic alterations of cluster I PCPGs compared with cluster II PCPGs, which usually present as benign tumors. By targeting the signature molecular pathway, we investigated the therapeutic effect of ascorbic acid on PCPGs using in vitro and in vivo models.ResultsBy investigating PCPG cells with low SDHB levels, we show that pseudohypoxia resulted in elevated expression of iron transport proteins, including transferrin (TF), transferrin receptor 2 (TFR2), and the divalent metal transporter 1 (SLC11A2; DMT1), leading to iron accumulation. This iron overload contributed to elevated oxidative stress. Ascorbic acid at pharmacologic concentrations disrupted redox homeostasis, inducing DNA oxidative damage and cell apoptosis in PCPG cells with low SDHB levels. Moreover, through a preclinical animal model with PCPG allografts, we demonstrated that pharmacologic ascorbic acid suppressed SDHB-low metastatic lesions and prolonged overall survival.ConclusionsThe data here demonstrate that targeting redox homeostasis as a cancer vulnerability with pharmacologic ascorbic acid is a promising therapeutic strategy for SDHB-mutated PCPGs.
| S-EPMC7443979 | biostudies-literature
Project description:BackgroundGermline mutations of the tumor suppressor genes SDHB, SDHC and SDHD play a major role in hereditary paraganglioma and pheochromocytoma. These three genes encode subunits of succinate dehydrogenase (SDH), the mitochondrial tricarboxylic acid cycle enzyme and complex II component of the electron transport chain. The majority of variants of the SDH genes are missense and nonsense mutations. To date few large deletions of the SDH genes have been described.MethodsWe carried out gene deletion scanning using MLPA in 126 patients negative for point mutations in the SDH genes. We then proceeded to the molecular characterization of deletions, mapping breakpoints in each patient and used haplotype analysis to determine whether the deletions are due to a mutation hotspot or if a common haplotype indicated a single founder mutation.ResultsA novel deletion of exon 3 of the SDHB gene was identified in nine apparently unrelated Dutch patients. An identical 7905 bp deletion, c.201-4429_287-933del, was found in all patients, resulting in a frameshift and a predicted truncated protein, p.Cys68HisfsX21. Haplotype analysis demonstrated a common haplotype at the SDHB locus. Index patients presented with pheochromocytoma, extra-adrenal PGL and HN-PGL. A lack of family history was seen in seven of the nine cases.ConclusionThe identical exon 3 deletions and common haplotype in nine patients indicates that this mutation is the first Dutch SDHB founder mutation. The predominantly non-familial presentation of these patients strongly suggests reduced penetrance. In this small series HN-PGL occurs as frequently as pheochromocytoma and extra-adrenal PGL.
| S-EPMC2670821 | biostudies-literature
Project description:Pheochromocytoma and paragangliomas (PCC/PGL) are neuroendocrine tumors that arise from chromaffin cells of the adrenal medulla and sympathetic/parasympathetic ganglia, respectively. Of clinical relevance regarding diagnosis is the highly variable presentation of symptoms in PCC/PGL patients. To date, the clear-cut correlations between the genotypes and phenotypes of PCC/PGL have not been entirely established. In this study, we reviewed the medical records of PCC/PGL patients with pertinent clinical, laboratory and genetic information. Next-generation sequencing (NGS) performed on patient samples revealed specific germline mutations in the SDHB (succinate dehydrogenase complex iron-sulfur subunit B) and SDHD (succinate dehydrogenase complex subunit D) genes and these mutations were validated by Sanger sequencing. Of the 119 patients, two were identified with SDHB mutation and one with SDHD mutation. Immunohistochemical (IHC) staining was used to analyze the expression of these mutated genes. The germline mutations identified in the SDH genes were c343C>T and c.541-542A>G in the SDHB gene and c.334-337delACTG in the SDHD gene. IHC staining of tumors from the c.343C>T and c.541-2A>G carriers showed positive expression of SDHB. Tumors from the c.334-337delACTG carrier showed no expression of SDHD and a weak diffused staining pattern for SDHB. We strongly recommend genetic testing for suspected PCC/PGL patients with a positive family history, early onset of age, erratic hypertension, recurrence or multiple tumor sites and loss of SDHB and/or SDHD expression. Tailored personal management should be conducted once a patient is confirmed as an SDHB and/or SDHD mutation carrier or diagnosed with PCC/PGL.
| S-EPMC6240141 | biostudies-other
Project description:The most common genetic backgrounds of hereditary paraganglioma and pheochromocytoma (PPGL) are SDHx germline mutations. Given the fact that the immunohistochemistry (IHC) result for SDHB is always negative regardless of the type of SDHx mutation, we aimed to evaluate the efficacy of using SDHB IHC for screening SDHx mutations in PPGL cases. In total, 52 patients who underwent surgery for PPGL treatment between 2006 and 2020 and underwent genetic analysis at diagnosis were included. Tissue microarrays (TMAs) were constructed with PPGL tissues and IHC for SDHB was performed on TMA sections. All 10 patients with SDHB-negative IHC contained SDHB or SDHD mutations. The genetic test results of patients with SDHB-weakly positive IHC varied (one SDHB, two RET, one VHL, and three unknown gene mutations). There were no SDHx mutations in the SDHB-positive IHC group. Six patients with weakly positive SDHB IHC with primarily unknown genetic status were re-called and underwent next-generation sequencing. None of them had SDHx mutations. In conclusion, SDHB-negative IHC is a cost-effective and reliable method to predict SDHx mutations. However, in the case of weakly positive SDHB staining, an additional gene study should be considered.
| S-EPMC8301322 | biostudies-literature
Project description:Abstract Background: SDHB immunostaining can be used to functionally characterize SDH status in PCC and PGL. Assessing SDHB expression on tumors is inexpensive and can be used as an alternative to genetic testing. More importantly, assessment of SDHB expression can be of value in interpreting Variant of Unknown Significance (VUS) in SDH related genes. Objective: To investigate the effectiveness of SDHB immunostaining as an initial screening tool in identifying germline SDH mutations and the value of SDHB assessment in the clinical characterization of our patient cohort. Design: Prospective and retrospective analysis of 57 randomly selected patients with PCC and PGL from the year 1997 to 2018. Setting: In our institution on patients referred from London and South East England including Kent, Surrey and Sussex. Patients: Predominant Caucasian Population with diverse ethnicities. 57 patients - 34 patients (14M & 20F) with PGL and 25 with PCC (15M &10F). Age (mean: 41years at diagnosis with range 9-80 years). 2 patients had both PCC & PGL and multifocal PGLs were identified in few patients with SDHD and SDHB mutation. There were 65 tumors in total included in this study. Intervention: Resected tumor SDHB immunostaining with Sigma prestige antibodies (HPA002868 100UL - Anti-SDHB Rabbit monoclonal antibody) at a dilution of 1:1000. Genetic testing performed on predominant candidate genes. Main outcome measures: Concordance of SDHB loss of expression with presence of pathogenic mutation in candidate SDH genes. Secondarily, to explore SDHB immunostaining in our patient cohort with VUS in candidate genes. Results: SDHB immunostaining was negative in 22/23 tumors in patients with confirmed SDH mutation (false negative = 1 SDHB PCC where it was weak (+)). The staining was positive in 23/24 sporadic tumors, 10/11 VUS (in SDH, MAX and TMEM genes - both PCCs & PGLs), 2/2 PCCs in MEN-2, 2/2 PCCs in NF-1 and 2/3 PCCs in VHL. The negative immunostaining in 1 PGL with VUS in SDHB may imply lack of SDH enzyme activity and hence suggestive of a pathological mutation. The sensitivity is 96% and the specificity approaches 93% if the weak positive SDHB immunostaining with SDHD and VHL tumors were to be considered concordant. The concordance was 95% in the PGL group alone. Conclusions: SDHB immunostaining is a cost effective addition to PGL and PCC tumor characterization and performs with high sensitivity and specificity. SDH functional characterization has an important role in the management of patients who do not satisfy the current criteria for genetic testing (UK genetics testing directory for PCC/PGL). 18% of patients had VUS in a SDH related gene and we have found that SDHB immunostaining provided helpful information to inform follow-up and cascade screening decisions in this group.
| S-EPMC6552923 | biostudies-literature
Project description:IntroductionPheochromocytomas and paragangliomas (PCC/PGL) are rare neuroendocrine tumors and can secrete catecholamine. Previous studies have found that SDHB immunohistochemistry (IHC) can predict SDHB germline gene mutation, and SDHB mutation is closely associated with tumor progression and metastasis. This study aimed to clarify the potential effect of SDHB IHC as a predictive marker for tumor progression in PCC/PGL patients.MethodsWe included PCC/PGL patients diagnosed in Ruijin Hospital, Shanghai Jiao Tong University School of Medicine from 2002 to 2014 for retrospective analysis and discovered that SDHB (-) staining patients had poorer prognoses. Then we examined SDHB protein expression by IHC on all tumors in the prospective series, which was composed of patients from 2015 to 2020 in our center.ResultsIn the retrospective series, the median follow-up was 167 months, and during follow-up, 14.4% (38/264) patients developed metastasis or recurrence, and 8.0% (22/274) patients died. Retrospective analysis revealed that 66.7% (6/9) of participants in the SDHB (-) group and 15.7% (40/255) of those in the SDHB (+) group developed progressive tumors (OR: 10.75, 95% CI: 2.72-52.60, P=0.001), and SDHB (-) was independently associated with poor outcomes after adjusting by other clinicopathological parameters (OR: 11.68, 95% CI: 2.58-64.45, P=0.002). SDHB (-) patients had shorter disease-free survival (DFS) and overall survival (OS) (P<0.001) and SDHB (-) was significantly associated with shorter median DFS (HR: 6.89, 95% CI: 2.41-19.70, P<0.001) in multivariate cox proportional hazard analysis. In the prospective series, the median follow-up was 28 months, 4.7% (10/213) patients developed metastasis or recurrence, and 0.5% (1/217) patient died. For the prospective analysis, 18.8% (3/16) of participants in the SDHB (-) group had progressive tumors compared with 3.6% (7/197) in the SDHB (+) group (RR: 5.28, 95% CI: 1.51-18.47, P=0.009), statistical significance remained (RR: 3.35, 95% CI: 1.20-9.38, P=0.021) after adjusting for other clinicopathological factors.ConclusionsOur findings demonstrated patients with SDHB (-) tumors had a higher possibility of poor outcomes, and SDHB IHC can be regarded as an independent biomarker of prognosis in PCC/PGL.
| S-EPMC10061060 | biostudies-literature
Project description:BackgroundPheochromocytomas (PCCs) and paragangliomas (PGLs) are neuroendocrine tumors that are mostly benign. Metastatic disease does occur in about 10% of cases of PCC and up to 25% of PGL, and for these patients no effective therapies are available. Patients with mutations in the succinate dehydrogenase subunit B (SDHB) gene tend to have metastatic disease. We hypothesized that a down-regulation in the active succinate dehydrogenase B subunit should result in notable changes in cellular metabolic profile and could present a vulnerability point for successful pharmacological targeting.MethodsMetabolomic analysis was performed on human hPheo1 cells and shRNA SDHB knockdown hPheo1 (hPheo1 SDHB KD) cells. Additional analysis of 115 human fresh frozen samples was conducted. In vitro studies using N1,N11-diethylnorspermine (DENSPM) and N1,N12- diethylspermine (DESPM) treatments were carried out. DENSPM efficacy was assessed in human cell line derived mouse xenografts.ResultsComponents of the polyamine pathway were elevated in hPheo1 SDHB KD cells compared to wild-type cells. A similar observation was noted in SDHx PCC/PGLs tissues compared to their non-mutated counterparts. Specifically, spermidine, and spermine were significantly elevated in SDHx-mutated PCC/PGLs, with a similar trend in hPheo1 SDHB KD cells. Polyamine pathway inhibitors DENSPM and DESPM effectively inhibited growth of hPheo1 cells in vitro as well in mouse xenografts.ConclusionsThis study demonstrates overactive polyamine pathway in PCC/PGL with SDHB mutations. Treatment with polyamine pathway inhibitors significantly inhibited hPheo1 cell growth and led to growth suppression in xenograft mice treated with DENSPM. These studies strongly implicate the polyamine pathway in PCC/PGL pathophysiology and provide new foundation for exploring the role for polyamine analogue inhibitors in treating metastatic PCC/PGL. PRéCIS: Cell line metabolomics on hPheo1 cells and PCC/PGL tumor tissue indicate that the polyamine pathway is activated. Polyamine inhibitors in vitro and in vivo demonstrate that polyamine inhibitors are promising for malignant PCC/PGL treatment. However, further research is warranted.
| S-EPMC7482423 | biostudies-literature
Project description:BackgroundGermline mutations in the succinate dehydrogenase complex genes SDHB, SDHC, and SDHD predispose to pheochromocytomas and paragangliomas. Here, we examine the SDHB, SDHC, and SDHD mutation spectrum in the Danish population by screening of 143 Danish pheochromocytoma and paraganglioma patients.MethodsMutational screening was performed by Sanger sequencing or next-generation sequencing. The frequencies of variants of unknown clinical significance, e.g. intronic, missense, and synonymous variants, were determined using the Exome Aggregation Consortium database, while the significance of missense mutations was predicted by in silico and loss of heterozygosity analysis when possible.ResultsWe report 18 germline variants; nine in SDHB, six in SDHC, and three in SDHD. Of these 18 variants, eight are novel. We classify 12 variants as likely pathogenic/pathogenic, one as likely benign, and five as variants of unknown clinical significance.ConclusionsIdentifying and classifying SDHB, SDHC, and SDHD variants present in the Danish population will augment the growing knowledge on variants in these genes and may support future clinical risk assessments.
| S-EPMC4898401 | biostudies-literature
Project description:The pheochromocytomas are an important cause of secondary hypertension. Although pheochromocytoma susceptibility may be associated with germline mutations in the tumor-suppressor genes VHL and NF1 and in the proto-oncogene RET, the genetic basis for most cases of nonsyndromic familial pheochromocytoma is unknown. Recently, pheochromocytoma susceptibility has been associated with germline SDHD mutations. Germline SDHD mutations were originally described in hereditary paraganglioma, a dominantly inherited disorder characterized by vascular tumors in the head and the neck, most frequently at the carotid bifurcation. The gene products of two components of succinate dehydrogenase, SDHC and SDHD, anchor the gene products of two other components, SDHA and SDHB, which form the catalytic core, to the inner-mitochondrial membrane. Although mutations in SDHC and in SDHD may cause hereditary paraganglioma, germline SDHA mutations are associated with juvenile encephalopathy, and the phenotypic consequences of SDHB mutations have not been defined. To investigate the genetic causes of pheochromocytoma, we analyzed SDHB and SDHC, in familial and in sporadic cases. Inactivating SDHB mutations were detected in two of the five kindreds with familial pheochromocytoma, two of the three kindreds with pheochromocytoma and paraganglioma susceptibility, and 1 of the 24 cases of sporadic pheochromocytoma. These findings extend the link between mitochondrial dysfunction and tumorigenesis and suggest that germline SDHB mutations are an important cause of pheochromocytoma susceptibility.
| S-EPMC1226047 | biostudies-literature
Project description:Cyclooxygenase 2 (COX-2) is a key enzyme of the tumorigenesis-inflammation interface and can be induced by hypoxia. A pseudohypoxic transcriptional signature characterizes pheochromocytomas and paragangliomas (PPGLs) of the cluster I, mainly represented by tumors with mutations in von Hippel-Lindau (VHL), endothelial PAS domain-containing protein 1 (EPAS1), or succinate dehydrogenase (SDH) subunit genes. The aim of this study was to investigate a possible association between underlying tumor driver mutations and COX-2 in PPGLs. COX-2 gene expression and immunoreactivity were examined in clinical specimens with documented mutations, as well as in spheroids and allografts derived from mouse pheochromocytoma (MPC) cells. COX-2 in vivo imaging was performed in allograft mice. We observed significantly higher COX-2 expression in cluster I, especially in VHL-mutant PPGLs, however, no specific association between COX-2 mRNA levels and a hypoxia-related transcriptional signature was found. COX-2 immunoreactivity was present in about 60% of clinical specimens as well as in MPC spheroids and allografts. A selective COX-2 tracer specifically accumulated in MPC allografts. This study demonstrates that, although pseudohypoxia is not the major determinant for high COX-2 levels in PPGLs, COX-2 is a relevant molecular target. This potentially allows for employing selective COX-2 inhibitors as targeted chemotherapeutic agents and radiosensitizers. Moreover, available models are suitable for preclinical testing of these treatments.
| S-EPMC6627450 | biostudies-literature