Endoscopic Complications Are More Frequent in Levodopa-Carbidopa Intestinal Gel Treatment via JET-PEG in Parkinson's Disease Patients Compared to Nutritional PEG in Non-Parkinson's Disease Patients.

Background: To date, no studies comparing complication rates between patients with nutritional percutaneous endoscopic gastrostomy (N-PEG) and Parkinson's disease (PD) patients with percutaneous endoscopic gastro-jejunostomy (JET-PEG) for treatment administration have been published. Our study aimed to compare complication rates and the number of re-endoscopies between N-PEG and JET-PEG patients. Methods: Individuals requiring N-PEG or JET-PEG insertion between 2014 and 2021 were included in this single-center retrospective observational study. Complications were divided into time-related medical and technical complications. Reasons for post-insertion re-endoscopies and their number were also analyzed. Results: Eighty-seven subjects, 47 (54.02%) in JET-PEG group and 40 (45.98%) in the N-PEG group, were included. Early and technical complications were more frequent in JET-PEG vs. N-PEG subjects (70% vs. 10% [p < 0.001], and 54.5% vs. 5.1% [p < 0.001], respectively). The presence of psychiatric disease was associated with a higher number of early complications (p < 0.002). All three types of complications were significantly more frequent in subjects where a healthcare professional did not handle PEG (p < 0.001). Subjects with JET-PEG required a higher number of re-endoscopies compared to the N-PEG group (57.1% vs. 35%, p = 0.05). Conclusions: Complications are significantly more common in individuals with JET-PEG than those with N-PEG, which can be attributed to higher mobility in PD patients.

Germline SUCLG2 Variants in Patients With Pheochromocytoma and Paraganglioma.

BACKGROUND: Pheochromocytoma and paraganglioma (PPGL) are neuroendocrine tumors with frequent mutations in genes linked to the tricarboxylic acid cycle. However, no pathogenic variant has been found to date in succinyl-CoA ligase (SUCL), an enzyme that provides substrate for succinate dehydrogenase (SDH; mitochondrial complex II [CII]), a known tumor suppressor in PPGL. METHODS: A cohort of 352 patients with apparently sporadic PPGL underwent genetic testing using a panel of 54 genes developed at the National Institutes of Health, including the SUCLG2 subunit of SUCL. Gene deletion, succinate levels, and protein levels were assessed in tumors where possible. To confirm the possible mechanism, we used a progenitor cell line, hPheo1, derived from a human pheochromocytoma, and ablated and re-expressed SUCLG2. RESULTS: We describe 8 germline variants in the guanosine triphosphate-binding domain of SUCLG2 in 15 patients (15 of 352, 4.3%) with apparently sporadic PPGL. Analysis of SUCLG2-mutated tumors and SUCLG2-deficient hPheo1 cells revealed absence of SUCLG2 protein, decrease in the level of the SDHB subunit of SDH, and faulty assembly of the complex II, resulting in aberrant respiration and elevated succinate accumulation. CONCLUSIONS: Our study suggests SUCLG2 as a novel candidate gene in the genetic landscape of PPGL. Large-scale sequencing may uncover additional cases harboring SUCLG2 variants and provide more detailed information about their prevalence and penetrance.

Clinical characteristics and outcomes of SDHB-related pheochromocytoma and paraganglioma in children and adolescents.

PURPOSE: Pheochromocytomas/paragangliomas (PHEOs/PGLs) are rare in children with only a few SDHB mutation-related cases. Previous studies on children were conducted in small cohorts. This large set of pediatric patients provides robust data in the evaluation of clinical outcomes. METHODS: Sixty-four pediatric PHEO/PGL patients with SDHB germline mutations were included in the present study. The clinical presentation, disease course, and survival rate were evaluated. RESULTS: Thirty-eight males and 26 females were diagnosed with PHEO/PGL at a median age of 13 years. The majority of patients displayed norepinephrine hypersecretion and 73.44% initially presented with a solitary tumor. Metastases developed in 70% of patients at the median age of 16 years and were mostly diagnosed first 2 years and in years 12-18 post-diagnosis. The presence of metastases at the time of diagnosis had a strong negative impact on survival in males but not in females. The estimated 5-, 10-, and 20-year survival rates were 100%, 97.14%, and 77.71%, respectively. CONCLUSION: The present report has highlighted several important aspects in the management of pediatric patients with SDHB mutations associated-PHEO/PGL. Initial diagnostic evaluation of SDHB mutation carriers should be started at age of 5-6 years with initial work-up focusing on abdominal region. Thorough follow-up is crucial first 2 years post-diagnosis and more frequent follow-ups are needed in years 10-20 post-diagnosis due to the increased risk of metastases. Although this age group developed metastasis as early as 5 years from diagnosis, we have shown that the overall 20-year prognosis and survival are good.

The Significant Reduction or Complete Eradication of Subcutaneous and Metastatic Lesions in a Pheochromocytoma Mouse Model after Immunotherapy Using Mannan-BAM, TLR Ligands, and Anti-CD40.

Therapeutic options for metastatic pheochromocytoma/paraganglioma (PHEO/PGL) are limited. Here, we tested an immunotherapeutic approach based on intratumoral injections of mannan-BAM with toll-like receptor ligands into subcutaneous PHEO in a mouse model. This therapy elicited a strong innate immunity-mediated antitumor response and resulted in a significantly lower PHEO volume compared to the phosphate buffered saline (PBS)-treated group and in a significant improvement in mice survival. The cytotoxic effect of neutrophils, as innate immune cells predominantly infiltrating treated tumors, was verified in vitro. Moreover, the combination of mannan-BAM and toll-like receptor ligands with agonistic anti-CD40 was associated with increased mice survival. Subsequent tumor re-challenge also supported adaptive immunity activation, reflected primarily by long-term tumor-specific memory. These results were further verified in metastatic PHEO, where the intratumoral injections of mannan-BAM, toll-like receptor ligands, and anti-CD40 into subcutaneous tumors resulted in significantly less intense bioluminescence signals of liver metastatic lesions induced by tail vein injection compared to the PBS-treated group. Subsequent experiments focusing on the depletion of T cell subpopulations confirmed the crucial role of CD8+ T cells in inhibition of bioluminescence signal intensity of liver metastatic lesions. These data call for a new therapeutic approach in patients with metastatic PHEO/PGL using immunotherapy that initially activates innate immunity followed by an adaptive immune response.

Effective cancer immunotherapy based on combination of TLR agonists with stimulation of phagocytosis.

Immunotherapy emerges as a fundamental approach in cancer treatment. Up to date, the efficacy of numerous different immunotherapies has been evaluated. The use of microorganisms or their parts for immune cell activation, referred to as Pathogen-Associated Molecular Patterns (PAMPs), represents highly promising concept. The therapeutic effect of PAMPs can be further amplified by suitable combination of different types of PAMPs such as Toll like receptor (TLR) agonists and phagocytosis activating ligands. Previously, we used the combination of phagocytosis activating ligand (mannan) and mixture of TLR agonists (resiquimod (R-848), poly(I:C), inactivated Listeria monocytogenes) for successful treatment of melanoma in murine B16-F10 model. In the present study, we optimized the composition and timing of previously used mixture. Therapeutic mixture based on well-defined chemical compounds consisted of mannan anchoring to tumor cell surface by biocompatible anchor for membranes (BAM) and TLR agonists resiquimod, poly(I:C), and lipoteichoic acid (LTA). The optimization resulted in (1) eradication of advanced stage progressive melanoma in 83% of mice, (2) acquisition of resistance to tumor re-transplantation, and (3) potential anti-metastatic effect. After further investigation of mechanisms, underlying anti-tumor responses, we concluded that both innate and adaptive immunity are activated and involved in these processes. We tested the efficacy of our treatment in Panc02 murine model of aggressive pancreatic tumor as well. Simultaneous application of agonistic anti-CD40 antibody was necessary to achieve effective therapeutic response (80% recovery) in this model. Our results suggest that herein presented immunotherapeutic approach is a promising cancer treatment strategy with the ability to eradicate not only primary tumors but also metastases.

Genomic Landscape of Pheochromocytoma and Paraganglioma.

Recent comprehensive molecular analysis allowed the identification of unique molecular signatures in pheochromocytomas (PHEOs) and paragangliomas (PGLs). Here we summarize the main pathway clusters activated by PHEO- and PGL-susceptibility genes: pseudohypoxic, kinase, and Wnt signaling. Molecular characterization and clustering of PHEOs and PGLs may help in the application of principles of personalized medicine and in decision making for targeted therapy of these tumors.

Contribution of Genetic Factors to Lower DHEAS in Patients with Rheumatoid Arthritis.

OBJECTIVE: Lower production of adrenal androgens has been confirmed in females with rheumatoid arthritis (RA); however, the mechanisms of this finding are not completely understood. The aim of our study was to assess the contribution of genetic factors associated with variability of dehydroepiandrosterone sulfate (DHEAS) levels to lower DHEAS in female RA patients. METHODS: 448 RA and 648 healthy controls were genotyped for single-nucleotide polymorphisms (SNPs) in genes ZKSCAN5 (rs11761528), SULT2A1 (rs2637125), HHEX (rs2497306), and ARPC1A (rs740160). Serum DHEAS concentrations were measured in 112 RA patients and 91 healthy women. RESULTS: The allele frequencies in DHEAS-related loci were similar in RA and controls. RA patients had significantly lower serum DHEAS concentrations compared to healthy women. The cumulative number of alleles associated with lower DHEAS within genes ZKSCAN5, SULT2A1, HHEX, and ARPC1A present in each individual negatively correlated with DHEAS levels in RA patients, but not in controls. Linear regression analysis showed significant effect of polymorphisms in genes ZKSCAN5 and ARPC1A on serum DHEAS levels in female RA patients but not in the control group. CONCLUSION: Our findings suggest that complex interactions exist between genotype and adrenal androgen hypofunction in RA.

PHEOCHROMOCYTOMA: A GENETIC AND DIAGNOSTIC UPDATE.

OBJECTIVE: Pheochromocytomas and paragangliomas (PPGLs) are neuroendocrine tumors derived from adrenal or extra-adrenal locations, respectively. Upon suspicion of PPGL, specific metabolomic, molecular, biochemical, imaging, and histopathologic studies are performed to prove, localize, treat, and monitor disease progression. Improved diagnostic tools allow physicians to accurately diagnose PPGL, even in patients presenting with small (<1 cm) or biochemically silent tumors, which previously delayed proper detection and treatment. METHODS: This review outlines the most updated approach to PPGL patients and presents a new diagnostic protocol for physicians to increase earlier tumor identification and accurately assess metastatic behavior. CONCLUSION: We present the most recent advances in genetics, epigenetics, metabolomics, biochemical, and imaging diagnoses of this rare tumor to properly assess disease, decide treatment options, and manage follow-up. We also elaborate on new therapeutic perspectives in these very rare neoplastic entities. ABBREVIATIONS: ATRX = ATRX chromatin remodeler; ccRCC = clear cell renal cell carcinoma; c-MYC = MYC proto oncognene; CT = computed tomography; DOTATATE = DOTA-octreotate; EGLN1/2 = egl-9 family hypoxia inducible factor 1/2; EGLN2/PHD1 = egl-9 family hypoxia inducible factor 2; EPAS1/HIF2A = endothelial PAS domain protein 2/hypoxia-inducible factor 2α; ERK = extracellular signal-regulated kinase; HIFs = hypoxia-inducible factors; HIF-α = hypoxia-inducible factor alpha; HNPGLs = head and neck paragangliomas; 177Lu-DOTATATE = lutetium octreotate; MAX = myc-associated factor X; MDH2 = malate dehydrogenase; MIBG = metaiodobenzylguanidine; MN = metanephrine; MRI = magnetic resonance imaging; mTOR = mammalian target of rapamycin; NETs = neuroendocrine tumors; NF1 = neurofibromin 1; NMN = normetanephrine; PHD = prolyl hydroxylase domain protein; PI3K = phosphoinositide 3-kinase; PPGLs = pheochromocytoma and paragangliomas; PRRT = peptide receptor radionuclide therapy; Pvhl = von Hippel-Lindau protein; RAS = rat sarcoma oncogene; RET = rearranged during transfection proto-oncogene; SDH = succinate dehydrogenase; SDHA, -B, -C, -D = succinate dehydrogenase subunits A, B, C, D; SDHAF2 = succinate dehydrogenase complex assembly factor 2; SDHB, C, D = succinate dehydrogenase subunits B, C, D; SDHx = succinate dehydrogenase subunits; SSTRs = somatostatin receptors; VHL = von Hippel-Lindau.

[Diagnosis and management of metastatic pheochromocytoma and paraganglioma]. / Diagnostika a manazment metastatického feochromocytómu a paragangliómu.

Pheochromocytoma (PHEO) and paraganglioma (PGL) are rare catecholamine-producing neuroendocrine tumors arising from adrenal medulla or extra-adrenal sympathetic and parasympathetic ganglia. Most of the PHEOs/PGLs are benign tumors, but metastatic disease is common, especially in patients with particular genetic background. Although PHEOs/PGLs were described more than a century ago, diagnosis and therapy of metastatic disease are still challenging. Advances in understanding molecular and metabolic changes associated with tumorigenesis lead us to identification of the background of these tumors. Novel information allowed for development of more precise diagnostic methods and molecular therapeutic targets identification, which will improve care of patients with metastatic PHEO/PGL.Key words: diagnostics - management - paraganglioma - pheochromocytoma - therapy.

SDHB-related pheochromocytoma and paraganglioma penetrance and genotype-phenotype correlations.

PURPOSE: Succinate dehydrogenase subunit B (SDHB) gene mutations are associated with an aggressive clinical disease course of pheochromocytoma/paraganglioma (PHEO/PGL). Limited information is available concerning PHEO/PGL penetrance among SDHB mutation carriers with regards to primary tumor location, specific mutation type, and gender. We assessed PHEO/PGL penetrance in SDHB mutation carriers and described the clinical presentation and disease course. METHODS: Asymptomatic relatives (N = 611) of 103 index patients were tested for SDHB mutations. Mutation carriers (N = 328) were offered PHEO/PGL screening, of which 241 participated and were included in penetrance analysis. For additional disease outcome analysis, the 103 index patients and 40 screened individuals who developed PHEO/PGL were included. Clinical data were collected between October 2004 and June 2016. RESULTS: Forty (16.60%) of the 241 screened individuals developed PHEO/PGL during the study. The penetrance estimate in this population was 49.80% (95% CI 29-74.9) at 85 years. A significantly higher age-related penetrance of disease was observed in males compared to females, with 50% penetrance achieved at age 74 vs. not reached. Age-related penetrance analysis demonstrated 4 mutations (Ile127Ser, IVS1+1G>T, Exon 1 deletion, Arg90X) presenting with a slower rate of disease development (50% penetrance ages, respectively: not achieved, 70, 63, 61 years) compared to Arg46X and Val140Phe mutations (50% penetrance at 38 years). CONCLUSIONS: Here, we found a higher estimated penetrance compared to several other studies, and a striking difference in age-related penetrance between male and female SDHB mutation carriers with no association between mutation and gender or tumor location.

Innate immunity based cancer immunotherapy: B16-F10 murine melanoma model.

BACKGROUND: Using killed microorganisms or their parts to stimulate immunity for cancer treatment dates back to the end of 19th century. Since then, it undergone considerable development. Our novel approach binds ligands to the tumor cell surface, which stimulates tumor phagocytosis. The therapeutic effect is further amplified by simultaneous application of agonists of Toll-like receptors. We searched for ligands that induce both a strong therapeutic effect and are safe for humans. METHODS: B16-F10 murine melanoma model was used. For the stimulation of phagocytosis, mannan or N-formyl-methionyl-leucyl-phenylalanine, was covalently bound to tumor cells or attached using hydrophobic anchor. The following agonists of Toll-like receptors were studied: monophosphoryl lipid A (MPLA), imiquimod (R-837), resiquimod (R-848), poly(I:C), and heat killed Listeria monocytogenes. RESULTS: R-848 proved to be the most suitable Toll-like receptor agonist for our novel immunotherapeutic approach. In combination with covalently bound mannan, R-848 significantly reduced tumor growth. Adding poly(I:C) and L. monocytogenes resulted in complete recovery in 83% of mice and in their protection from the re-transplantation of melanoma cells. CONCLUSION: An efficient cancer treatment results from the combination of Toll-like receptor agonists and phagocytosis stimulating ligands bound to the tumor cells.

Pheochromocytoma: The First Metabolic Endocrine Cancer.

Dysregulated metabolism is one of the key characteristics of cancer cells. The most prominent alterations are present during regulation of cell respiration, which leads to a switch from oxidative phosphorylation to aerobic glycolysis. This metabolic shift results in activation of numerous signaling and metabolic pathways supporting cell proliferation and survival. Recent progress in genetics and metabolomics has allowed us to take a closer look at the metabolic changes present in pheochromocytomas (PHEO) and paragangliomas (PGL). These neuroendocrine tumors often exhibit dysregulation of mitochondrial metabolism, which is driven by mutations in genes encoding Krebs cycle enzymes or by activation of hypoxia signaling. Present metabolic changes are involved in processes associated with tumorigenesis, invasiveness, metastasis, and resistance to various cancer therapies. In this review, we discuss the metabolic nature of PHEOs/PGLs and how unveiling the metabolic disturbances present in tumors could lead to identification of new biomarkers and personalized cancer therapies. Clin Cancer Res; 22(20); 5001-11. ©2016 AACR SEE ALL ARTICLES IN THIS CCR FOCUS SECTION, "ENDOCRINE CANCERS REVISING PARADIGMS".

Hypoxia-Inducible Factor 2α Mutation-Related Paragangliomas Classify as Discrete Pseudohypoxic Subcluster.

Recently, activating mutations of the hypoxia-inducible factor 2α gene (HIF2A/EPAS1) have been recognized to predispose to multiple paragangliomas (PGLs) and duodenal somatostatinomas associated with polycythemia, and ocular abnormalities. Previously, mutations in the SDHA/B/C/D, SDHAF2, VHL, FH, PHD1, and PHD2 genes have been associated with HIF activation and the development of pseudohypoxic (cluster-1) PGLs. These tumors overlap in terms of tumor location, syndromic presentation, and noradrenergic phenotype to a certain extent. However, they also differ especially by clinical outcome and by presence of other tumors or abnormalities. In the present study, we aimed to establish additional molecular differences between HIF2A and non-HIF2A pseudohypoxic PGLs. RNA expression patterns of HIF2A PGLs (n=6) from 2 patients were compared with normal adrenal medullas (n=8) and other hereditary pseudohypoxic PGLs (VHL: n=13, SDHB: n=15, and SDHD: n=14). Unsupervised hierarchical clustering showed that HIF2A PGLs made up a separate cluster from other pseudohypoxic PGLs. Significance analysis of microarray yielded 875 differentially expressed genes between HIF2A and other pseudohypoxic PGLs after normalization to adrenal medulla (false discovery rate 0.01). Prediction analysis of microarray allowed correct classification of all HIF2A samples based on as little as three genes (TRHDE, LRRC63, IGSF10; error rate: 0.02). Genes with the highest expression difference between normal medulla and HIF2A PGLs were selected for confirmatory quantitative reverse transcriptase polymerase chain reaction. In conclusion, HIF2A PGLs show a characteristic expression signature that separates them from non-HIF2A pseudohypoxic PGLs. Unexpectedly, the most significantly differentially expressed genes have not been previously described as HIF target genes.

Novel insights into the polycythemia-paraganglioma-somatostatinoma syndrome.

Worldwide, the syndromes of paraganglioma (PGL), somatostatinoma (SOM) and early childhood polycythemia are described in only a few patients with somatic mutations in the hypoxia-inducible factor 2 alpha (HIF2A). This study provides detailed information about the clinical aspects and course of 7 patients with this syndrome and brings into perspective these experiences with the pertinent literature. Six females and one male presented at a median age of 28 years (range 11-46). Two were found to have HIF2A somatic mosaicism. No relatives were affected. All patients were diagnosed with polycythemia before age 8 and before PGL/SOM developed. PGLs were found at a median age of 17 years (range 8-38) and SOMs at 29 years (range 22-38). PGLs were multiple, recurrent and metastatic in 100, 100 and 29% of all cases, and SOMs in 40, 40 and 60%, respectively. All PGLs were primarily norepinephrine-producing. All patients had abnormal ophthalmologic findings and those with SOMs had gallbladder disease. Computed tomography (CT) and magnetic resonance imaging revealed cystic lesions at multiple sites and hemangiomas in 4 patients (57%), previously thought to be pathognomonic for von Hippel-Lindau disease. The most accurate radiopharmaceutical to detect PGL appeared to be [18F]-fluorodihydroxyphenylalanine ([18F]-FDOPA). Therefore, [18F]-FDOPA PET/CT, not [68Ga]-(DOTA)-[Tyr3]-octreotate ([68Ga]-DOTATATE) PET/CT is recommended for tumor localization and aftercare in this syndrome. The long-term prognosis of the syndrome is unknown. However, to date no deaths occurred after 6 years follow-up. Physicians should be aware of this unique syndrome and its diagnostic and therapeutic challenges.

A Combination of CD28 (rs1980422) and IRF5 (rs10488631) Polymorphisms Is Associated with Seropositivity in Rheumatoid Arthritis: A Case Control Study.

INTRODUCTION: The aim of the study was to analyse genetic architecture of RA by utilizing multiparametric statistical methods such as linear discriminant analysis (LDA) and redundancy analysis (RDA). METHODS: A total of 1393 volunteers, 499 patients with RA and 894 healthy controls were included in the study. The presence of shared epitope (SE) in HLA-DRB1 and 11 SNPs (PTPN22 C/T (rs2476601), STAT4 G/T (rs7574865), CTLA4 A/G (rs3087243), TRAF1/C5 A/G (rs3761847), IRF5 T/C (rs10488631), TNFAIP3 C/T (rs5029937), AFF3 A/T (rs11676922), PADI4 C/T (rs2240340), CD28 T/C (rs1980422), CSK G/A (rs34933034) and FCGR3A A/C (rs396991), rheumatoid factor (RF), anti-citrullinated protein antibodies (ACPA) and clinical status was analysed using the LDA and RDA. RESULTS: HLA-DRB1, PTPN22, STAT4, IRF5 and PADI4 significantly discriminated between RA patients and healthy controls in LDA. The correlation between RA diagnosis and the explanatory variables in the model was 0.328 (Trace = 0.107; F = 13.715; P = 0.0002). The risk variants of IRF5 and CD28 genes were found to be common determinants for seropositivity in RDA, while positivity of RF alone was associated with the CTLA4 risk variant in heterozygous form. The correlation between serologic status and genetic determinants on the 1st ordinal axis was 0.468, and 0.145 on the 2nd one (Trace = 0.179; F = 6.135; P = 0.001). The risk alleles in AFF3 gene together with the presence of ACPA were associated with higher clinical severity of RA. CONCLUSIONS: The association among multiple risk variants related to T cell receptor signalling with seropositivity may play an important role in distinct clinical phenotypes of RA. Our study demonstrates that multiparametric analyses represent a powerful tool for investigation of mutual relationships of potential risk factors in complex diseases such as RA.

Pheochromocytoma: Gasping for Air.

There has been increasing evidence that pseudohypoxia--a phenomenon that we refer to as "gasping for air"--along with mitochondrial enzyme dysregulation play a crucial role in tumorigenesis, particularly in several hereditary pheochromocytomas (PHEOs) and paragangliomas (PGLs). Alterations in key tricarboxylic acids (TCA) cycle enzymes (SDH, FH, MDH2) have been shown to induce pseudohypoxia via activation of the hypoxia-inducible transcription factor (HIF) signaling pathway that is involved in tumorigenesis, invasiveness, and metastatic spread, including an association with resistance to various cancer therapies and worse prognosis. This review outlines the ongoing story of the pathogenesis of hereditary PHEOs/PGLs, showing the unique and most updated evidence of TCA cycle dysregulation that is tightly linked to hypoxia signaling.

Autoimmune thyroid disease and rheumatoid arthritis: relationship and the role of genetics.

Autoimmune thyroid disease (AITD), known as the most common organ-specific autoimmune disorder, is frequently accompanied by other organ and non-organ-specific autoimmune diseases, including rheumatoid arthritis (RA). Although the exact pathogenic mechanisms of the coexistence of autoimmune disorders are still not completely defined, genetics, immune defects, hormones and environmental factors may play key roles in polyautoimmunity. In this review, the prevalence of AITD and antithyroid autoantibodies in RA patients and rheumatic manifestations in association with thyroid autoimmunity are discussed. Finally, we review the role of genetics in the association of both AITD and RA, especially CTLA-4 and PTPN22 polymorphisms.

A new twist in neuroendocrine tumor research: Pacak-Zhuang syndrome, HIF-2α as the major player in its pathogenesis and future therapeutic options.

UNLABELLED: Backround. There is increasing evidence of the role of hypoxia or pseudohypoxia in tumorigenesis, including pheochromocytoma (PHEO) and paraganglioma (PGL). (Pseudo)hypoxia leads to activation of hypoxia-inducible transcription factors (HIFs) and thus, promotes the transcription of hypoxia-responsive genes which are involved in tumorigenesis. Recently identified is a new syndrome consisting of multiple and recurrent PGLs or PHEOs, somatostatinoma, and congenital polycythemia, due to somatic hypoxia-inducible factor 2α gene (HIF2A) mutations. METHODS AND RESULTS: PubMed and Web of Science online databases were used to search reviews and original articles on the HIF, PHEO/PGL, and Pacak-Zhuang syndrome. CONCLUSIONS: The novel somatic and germline gain-of-function HIF2A mutations described latterly emphasize the role of the HIF-2α in the PHEO/PGL development and these findings designate HIF, especially HIF-2α, as a promising treatment target.

Hypoxia-inducible factor signaling in pheochromocytoma: turning the rudder in the right direction.

Many solid tumors, including pheochromocytoma (PHEO) and paraganglioma (PGL), are characterized by a (pseudo)hypoxic signature. (Pseudo)hypoxia has been shown to promote both tumor progression and resistance to therapy. The major mediators of the transcriptional hypoxic response are hypoxia-inducible factors (HIFs). High levels of HIFs lead to transcription of hypoxia-responsive genes, which are involved in tumorigenesis. PHEOs and PGLs are catecholamine-producing tumors arising from sympathetic- or parasympathetic-derived chromaffin tissue. In recent years, substantial progress has been made in understanding the metabolic disturbances present in PHEO and PGL, especially because of the identification of some disease-susceptibility genes. To date, fifteen PHEO and PGL susceptibility genes have been identified. Based on the main transcription signatures of the mutated genes, PHEOs and PGLs have been divided into two clusters, pseudohypoxic cluster 1 and cluster 2, rich in kinase receptor signaling and protein translation pathways. Although these two clusters seem to show distinct signaling pathways, recent data suggest that both clusters are interconnected by HIF signaling as the important driver in their tumorigenesis, and mutations in most PHEO and PGL susceptibility genes seem to affect HIF-α regulation and its downstream signaling pathways. HIF signaling appears to play an important role in the development and growth of PHEOs and PGLs, which could suggest new therapeutic approaches for the treatment of these tumors.

New syndrome of paraganglioma and somatostatinoma associated with polycythemia.

PURPOSE: The occurrence of ≥ two distinct types of tumors, one of them paraganglioma (PGL), is unusual in an individual patient, except in hereditary cancer syndromes. PATIENTS AND METHODS: Four unrelated patients were investigated, with thorough clinical evaluation. Plasma and tissue catecholamines and metanephrines were measured by high-performance liquid chromatography. Anatomic and functional imaging were performed for tumor visualization. Germline and tumor tissue DNA were analyzed for hypoxia-inducible factor 2 alpha (HIF2A) mutations. The prolyl hydroxylation and stability of the mutant HIF2α protein, transcriptional activity of mutant HIF2A, and expression of hypoxia-related genes were also investigated. Immunohistochemical staining for HIF1/2α was performed on formalin-fixed, paraffin-embedded tumor tissue. RESULTS: Patients were found to have polycythemia, multiple PGLs, and duodenal somatostatinomas by imaging or biochemistry with somatic gain-of-function HIF2A mutations. Each patient carried an identical unique mutation in both types of tumors but not in germline DNA. The HIF2A mutations in these patients were clustered adjacent to an oxygen-sensing proline residue, affecting HIF2α interaction with the prolyl hydroxylase domain 2-containing protein, decreasing the hydroxylation of HIF2α, and reducing HIF2α affinity for the von Hippel-Lindau protein and its degradation. An increase in the half-life of HIF2α was associated with upregulation of the hypoxia-related genes EPO, VEGFA, GLUT1, and END1 in tumors. CONCLUSION: Our findings indicate the existence of a new syndrome with multiple PGLs and somatostatinomas associated with polycythemia. This new syndrome results from somatic gain-of-function HIF2A mutations, which cause an upregulation of hypoxia-related genes, including EPO and genes important in cancer biology.