Pheochromocytomas can usually be confirmed or excluded using currently available biochemical tests of catecholamine excess. Follow-up tests are, nevertheless, often required to distinguish false-positive from true-positive results. The glucagon stimulation test represents one such test; its diagnostic utility is, however, unclear.

In order to identify genetic factors related to thyroid cancer susceptibility, we adopted a candidate gene approach. We studied tag- and putative functional SNPs in genes involved in thyroid cell differentiation and proliferation, and in genes found to be differentially expressed in thyroid carcinoma. A total of 768 SNPs in 97 genes were genotyped in a Spanish series of 615 cases and 525 controls, the former comprising the largest collection of patients with this pathology from a single population studied to date. SNPs in an LD block spanning the entire FOXE1 gene showed the strongest evidence of association with papillary thyroid carcinoma susceptibility. This association was validated in a second stage of the study that included an independent Italian series of 482 patients and 532 controls. The strongest association results were observed for rs1867277 (OR[per-allele] = 1.49; 95%CI = 1.30-1.70; P = 5.9x10(-9)). Functional assays of rs1867277 (NM_004473.3:c.-283G>A) within the FOXE1 5' UTR suggested that this variant affects FOXE1 transcription. DNA-binding assays demonstrated that, exclusively, the sequence containing the A allele recruited the USF1/USF2 transcription factors, while both alleles formed a complex in which DREAM/CREB/alphaCREM participated. Transfection studies showed an allele-dependent transcriptional regulation of FOXE1. We propose a FOXE1 regulation model dependent on the rs1867277 genotype, indicating that this SNP is a causal variant in thyroid cancer susceptibility. Our results constitute the first functional explanation for an association identified by a GWAS and thereby elucidate a mechanism of thyroid cancer susceptibility. They also attest to the efficacy of candidate gene approaches in the GWAS era.

Von Hippel-Lindau (VHL)-associated hemangioblastomas (VHL-HB) arise in the central nervous system (CNS), and are a leading cause of morbidity and mortality in VHL disease. Currently, surgical resection is the most effective way to manage symptomatic VHL-HBs. Surgically unresectable VHL-HBs or those in frail patients are challenging problems. Therapies targeting oncologic and vascular endothelial growth factor (VEGF) pathways have failed to demonstrate tumor control. Our experience and previous reports on VHL-HB avidity to somatostatin analogues suggested somatostatin receptor (SSTR) expression in VHL-HBs, offering an alternative therapeutic strategy. We explored this possibility by demonstrating consistent histologic expression of SSTR1, 2a, 4, and 5 in VHL-HBs. We found that somatostatin analogue octreotide induces apoptosis in VHL-HB stromal cells in a dose-dependent fashion by BAX - caspase-3 pathway unrelated to canonical VHL pathway. When administered to a patient with unresectable symptomatic suprasellar hemangioblastoma, octreotide resulted in tumor volume reduction, symptom stabilization, and tumor cytopenia on repeat 68Ga-DOTA-TATE positron emission tomography (PET) within 6 months, suggesting tumor infarction. We conclude that VHL-HBs harbor multiple SSTR subtypes that offer actionable chemo-therapeutic strategy for management of symptomatic, unresectable tumors by somatostatin analogue therapy.

Hedgehog (Hh) proteins control animal development and tissue homeostasis. They activate gene expression by regulating processing, stability, and activation of Gli/Cubitus interruptus (Ci) transcription factors. Hh proteins are secreted and spread through tissue, despite becoming covalently linked to sterol during processing. Multiple mechanisms have been proposed to release Hh proteins in distinct forms; in Drosophila, lipoproteins facilitate long-range Hh mobilization but also contain lipids that repress the pathway. Here, we show that mammalian lipoproteins have conserved roles in Sonic Hedgehog (Shh) release and pathway repression. We demonstrate that lipoprotein-associated forms of Hh and Shh specifically block lipoprotein-mediated pathway inhibition. We also identify a second conserved release form that is not sterol-modified and can be released independently of lipoproteins (Hh-N*/Shh-N*). Lipoprotein-associated Hh/Shh and Hh-N*/Shh-N* have complementary and synergistic functions. In Drosophila wing imaginal discs, lipoprotein-associated Hh increases the amount of full-length Ci, but is insufficient for target gene activation. However, small amounts of non-sterol-modified Hh synergize with lipoprotein-associated Hh to fully activate the pathway and allow target gene expression. The existence of Hh secretion forms with distinct signaling activities suggests a novel mechanism for generating a diversity of Hh responses.

The molecular genetics of inherited phaeochromocytoma have received considerable attention, but the somatic genetic and epigenetic events that characterise tumourigenesis in sporadic phaeochromocytomas are less well defined. Previously, we found considerable overlap between patterns of promoter region tumour suppressor gene (TSG) hypermethylation in two neural crest tumours, neuroblastoma and phaeochromocytoma. In order to identify candidate biomarkers and epigenetically inactivated TSGs in phaeochromocytoma and neuroblastoma, we characterised changes in gene expression in three neuroblastoma cell lines after treatment with the demethylating agent 5-azacytidine. Promoter region methylation status was then determined for 28 genes that demonstrated increased expression after demethylation. Three genes HSP47, homeobox A9 (HOXA9) and opioid binding protein (OPCML) were methylated in >10% of phaeochromocytomas (52, 17 and 12% respectively). Two of the genes, epithelial membrane protein 3 (EMP3) and HSP47, demonstrated significantly more frequent methylation in neuroblastoma than phaeochromocytoma. These findings extend epigenotype of phaeochromocytoma and identify candidate genes implicated in sporadic phaeochromocytoma tumourigenesis.

Cancer cells without mitochondrial DNA (mtDNA) do not form tumors unless they reconstitute oxidative phosphorylation (OXPHOS) by mitochondria acquired from host stroma. To understand why functional respiration is crucial for tumorigenesis, we used time-resolved analysis of tumor formation by mtDNA-depleted cells and genetic manipulations of OXPHOS. We show that pyrimidine biosynthesis dependent on respiration-linked dihydroorotate dehydrogenase (DHODH) is required to overcome cell-cycle arrest, while mitochondrial ATP generation is dispensable for tumorigenesis. Latent DHODH in mtDNA-deficient cells is fully activated with restoration of complex III/IV activity and coenzyme Q redox-cycling after mitochondrial transfer, or by introduction of an alternative oxidase. Further, deletion of DHODH interferes with tumor formation in cells with fully functional OXPHOS, while disruption of mitochondrial ATP synthase has little effect. Our results show that DHODH-driven pyrimidine biosynthesis is an essential pathway linking respiration to tumorigenesis, pointing to inhibitors of DHODH as potential anti-cancer agents.

Gsα couples multiple receptors, including the melanocortin 4 receptor (MC4R), to intracellular cAMP generation. Germline inactivating Gsα mutations lead to obesity in humans and mice. Mice with brain-specific Gsα deficiency also develop obesity with reduced energy expenditure and locomotor activity, and impaired adaptive thermogenesis, but the underlying mechanisms remain unclear.

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.

Pheochromocytomas (PHEOs) and paragangliomas (PGLs) are rare, neuroendocrine tumors derived from adrenal or extra-adrenal chromaffin cells, respectively. Metastases are discovered in 3-36% of patients at the time of diagnosis. Currently, only suboptimal treatment options exist. Therefore, new therapeutic compounds targeting metastatic PHEOs/PGLs are urgently needed. Here, we investigated if anthracyclines were able to suppress the progression of metastatic PHEO. We explored their effects on experimental mouse PHEO tumor cells using in vitro and in vivo models, and demonstrated that anthracyclines, particularly idarubicin (IDA), suppressed hypoxia signaling by preventing the binding of hypoxia-inducible factor 1 and 2 (HIF-1 and HIF-2) to the hypoxia response element (HRE) sites on DNA. This resulted in reduced transcriptional activation of HIF target genes, including erythropoietin (EPO), phosphoglycerate kinase 1 (PGK1), endothelin 1 (EDN1), glucose transporter 1 (GLUT1), lactate dehydrogenase A (LDHA), and vascular endothelial growth factor (VEGFA), which consequently inhibited the growth of metastatic PHEO. Additionally, IDA downregulated hypoxia signaling by interfering with the transcriptional activation of HIF1A and HIF2A. Furthermore, our animal model demonstrated the dose-dependent suppressive effect of IDA on metastatic PHEO growth in vivo. Our results indicate that anthracyclines are prospective candidates for inclusion in metastatic PHEO/PGL therapy, especially in patients with gene mutations involved in the hypoxia signaling pathway.

The purpose of this study was to compare components of cardiometabolic risk and health behaviors of 20 family caregivers of allogeneic hematopoietic stem cell transplant patients to those of age, gender, and race/ethnicity-matched controls. A prospective, repeated measures design was used to compare cardiometabolic risk and health behaviors in caregivers and controls at three time-points: pre-transplantation, discharge, and six weeks post-discharge. Measures included components of metabolic syndrome, Reynolds Risk Score, NMR serum lipoprotein particle analyses, and the Health-Promoting Lifestyle Profile II (HPLP-II). Mixed-model repeated measure analyses were used. There were no between or within group differences in LDL cholesterol, HDL cholesterol, and triglycerides. There was a significant interaction effect between time and role in large VLDL concentration (VLDL-P) (F (2, 76) = 4.36, p = .016), with the trajectory of large VLDL-P increasing over time in caregivers while remaining stable in controls. Within caregivers, VLDL particle size (VLDL-Z) was significantly larger at time-point three compared to time-points one (p = .015) and two (p = .048), and VLDL-Z was significantly larger in caregivers than in controls at time point three (p = .012). HPLP-II scores were lower in caregivers than controls at all time-points (p < .01). These findings suggest that caregiving may have a bigger impact on triglycerides than on other lipids, and it is through this pathway that caregivers may be at increased cardiometabolic risk. More sensitive measurement methods, such as NMR lipoprotein particle analyses, may be able to detect early changes in cardiometabolic risk.

Proteasome inhibitors have been frequently used in treating hematologic and solid tumors. They are administered individually or in combination with other regimens, to prevent severe side effects and resistance development. Because they have been shown to be efficient and are pharmaceutically available, we tested the first Food and Drug Administration-approved proteasome inhibitor bortezomib alone and in combination with another proteasome inhibitor, salinosporamid A, in pheochromocytoma cells. Pheochromocytomas/Paragangliomas (PHEOs/PGLs) are neuroendocrine tumors for which no definite cure is yet available. Therefore, drugs with a wide spectrum of mechanisms of action are being tested to identify suitable candidates for PHEO/PGL treatment. In the current study, we show that bortezomib induces PHEO cell death via the apoptotic pathway in vitro and in vivo. The combination of bortezomib with salinosporamid A exhibits additive effect on these cells and inhibits proliferation, cell migration and invasion, and angiogenesis more potently than bortezomib alone. Altogether, we suggest these proteasome inhibitors, especially bortezomib, could be potentially tested in PHEO/PGL patients who might benefit from treatment with either the inhibitors alone or in combination with other treatment options.

Mosaic or somatic EPAS1 mutations are associated with a range of phenotypes including pheochromocytoma and/or paraganglioma (PPGL), polycythemia and somatostatinoma. The pathogenic potential of germline EPAS1 variants however is not well understood. We report a number of germline EPAS1 variants occurring in patients with PPGL, including a novel variant c.739C>A (p.Arg247Ser); a previously described variant c.1121T>A (p.Phe374Tyr); several rare variants, c.581A>G (p.His194Arg), c.2353C>A (p.Pro785Thr) and c.2365A>G (p.Ile789Val); a common variant c.2296A>C (p.Thr766Pro). We performed detailed functional studies to understand their pathogenic role in PPGL. In transient transfection studies, EPAS1/HIF-2α p.Arg247Ser, p.Phe374Tyr and p.Pro785Thr were all stable in normoxia. In co-immunoprecipitation assays, only the novel variant p.Arg247Ser showed diminished interaction with pVHL. A direct interaction between HIF-2α Arg247 and pVHL was confirmed in structural models. Transactivation was assessed by means of a HRE-containing reporter gene in transiently transfected cells, and significantly higher reporter activity was only observed with EPAS1/HIF-2α p.Phe374Tyr and p.Pro785Thr. In conclusion, three germline EPAS1 variants (c.739C>A (p.Arg247Ser), c.1121T>A (p.Phe374Tyr) and c.2353C>A (p.Pro785Thr)) all have some functional features in common with somatic activating mutations. Our findings suggest that these three germline variants are hypermorphic alleles that may act as modifiers to the expression of PPGLs.

The risk factors for severe COVID-19 are diverse, yet closely resemble the clinical manifestations of catecholamine excess states (eg, hypertension, cardiovascular disease, immune dysregulation, and hyperglycaemia), suggesting a potentially common basis for disease. Unfortunately, severe illness (eg, respiratory failure, compromised cardiac function, and shock) incurred by COVID-19 hinders the direct study of catecholamines in these patients, especially among those on multiple medications or those on adrenaline or noradrenaline infusions, or both. Phaeochromocytoma and paraganglioma (PPGL) are tumours that secrete catecholamines, namely adrenaline and noradrenaline, often in excess. PPGL are well studied disease processes in which the effects of catecholamines are easily discernible and therefore their potential biochemical and physiological influences in patients with COVID-19 can be explored. Because catecholamines are expected to have a role in patients with critical illness, patients on vasopressor infusions, and patients who sustain some acute and chronic physical stresses, the challenges involved in the management of catecholamine excess states are directly relevant to the treatment of patients with COVID-19. In this Personal View, we discuss the complex interplay between catecholamines and COVID-19, and the management of catecholamine excess states, while referencing relevant insights derived from the study of PPGL.

Over the past few years, next generation technologies have been applied to unravel the genetics of rare inherited diseases, facilitating the discovery of new susceptibility genes. We recently found germline DNMT3A gain-of-function variants in two patients with head and neck paragangliomas causing a characteristic hypermethylated DNA profile. Here, whole-exome sequencing identifies a novel germline DNMT3A variant (p.Gly332Arg) in a patient with bilateral carotid paragangliomas, papillary thyroid carcinoma and idiopathic intellectual disability. The variant, located in the Pro-Trp-Trp-Pro (PWWP) domain of the protein involved in chromatin targeting, affects a residue mutated in papillary thyroid tumors and located between the two residues found mutated in microcephalic dwarfism patients. Structural modelling of the variant in the DNMT3A PWWP domain predicts that the interaction with H3K36me3 will be altered. An increased methylation of DNMT3A target genes, compatible with a gain-of-function effect of the alteration, was observed in saliva DNA from the proband and in one independent acute myeloid leukemia sample carrying the same p.Gly332Arg variant. Although further studies are needed to support a causal role of DNMT3A variants in paraganglioma, the description of a new DNMT3A alteration in a patient with multiple clinical features suggests a heterogeneous phenotypic spectrum related to DNMT3A germline variants.

Hereditary leiomyomatosis and renal cell cancer syndrome (HLRCC) is a very rare hereditary disorder characterized by cutaneous leiomyomas (CLMs), uterine leiomyomas (ULMs), renal cysts (RCys) and renal cell cancers (RCCs). We aimed to describe the genetics, clinical features and potential genotype-phenotype associations in the largest cohort of fumarate hydratase enzyme mutation carriers known from Spain using a multicentre, retrospective study of individuals with a genetic or clinical diagnosis of HLRCC. We collected clinical information from medical records, analysed genetic variants and looked for genotype-phenotype associations. Analyses were performed using R 3.6.0. software. We included 197 individuals: 74 index cases and 123 relatives. CLMs were diagnosed in 65% of patients, ULMs in 90% of women, RCys in 37% and RCC in 10.9%. Twenty-seven different pathogenic variants were detected, 12 (44%) of them not reported previously. Patients with missense pathogenic variants showed higher frequencies of CLMs, ULMs and RCys, than those with loss-of-function variants (p = 0.0380, p = 0.0015 and p = 0.024, respectively). This is the first report of patients with HLRCC from Spain. The frequency of RCCs was lower than those reported in the previously published series. Individuals with missense pathogenic variants had higher frequencies of CLMs, ULMs and RCys.

Limited genetic factors were uncovered for the development of congenital anomalies of the kidney and urinary tract (CAKUT). We previously reported that a Holliday junction resolvase Gen1 was essential for early metanephric development in mice. This comprehensive follow-up study focused on the roles of Gen1 in late metanephric development. We found that Gen1 mutation impaired the late development of both kidney and urinary tract. In vivo and ex-vivo kidney primordia culture confirmed decreased ureteric bud branching in Gen1 mutants, which consequently caused hypoplasia. We also observed abnormal urinary tract development. Programmed apoptosis at the end of nephric duct disappeared in Gen1 mutants, which caused abnormal ureter-bladder connections, leading to vesicoureteral reflux (VUR) or ureterovesical junction obstruction (UVJO). Mechanistically, RNA-seq analysis proved that Gen1 mutation impaired the expression of multiple regulatory genes for the metanephric development, including Six2. Taken together, our study provides more insight into the roles of Gen1 in the development of the kidney and urinary tract, which may have potential clinical significance in the treatment and/or prevention of CAKUT.

Succinate dehydrogenase subunit B (SDHB) deficiency frequently occurs in cluster I pheochromocytomas and paragangliomas (PCPGs). SDHB-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 SDHB-deficient PCPG cells exhibit increased oxidative stress burden, which leads to elevated demands for glutathione metabolism. Mechanistically, nuclear factor erythroid 2-related factor 2 (NRF2)-guided glutathione de novo synthesis plays a key role in supporting cellular survival and the proliferation of SDHB-knockdown (SDHBKD) cells. NRF2 blockade not only disrupted ROS homeostasis in SDHB-deficient cells but also caused severe cytotoxicity by the accumulation of DNA oxidative damage. Brusatol, a potent NRF2 inhibitor, showed a promising effect in suppressing SDHBKD metastatic lesions in vivo, with prolonged overall survival in mice bearing PCPG allografts. Our findings highlight a novel therapeutic strategy of targeting the NRF2-driven glutathione metabolic pathway against SDHB-mutated PCPG.

Metastatic breast cancer (MBC) progressing after endocrine therapy frequently activates PI3K/AKT/mTOR pathway. The BOLERO-2 trial showed that everolimus-exemestane achieves increased progression free survival (PFS) compared with exemestane. However, there is great inter-patient variability in toxicity and response to exemestane-everolimus treatment. The objective of this study was to perform an exploratory study analyzing the implication of single nucleotide polymorphisms (SNPs) on outcomes from this treatment through a pharmacogenetic analysis.

We previously identified a novel syndrome in patients characterized by paraganglioma, somatostatinoma, and polycythemia. In these patients, polycythemia occurs long before any tumor develops, and tumor removal only partially corrects polycythemia, with recurrence occurring shortly after surgery. Genetic mosaicism of gain-of-function mutations of the EPAS1 gene (encoding HIF2α) located in the oxygen degradation domain (ODD), typically p.530-532, was shown as the etiology of this syndrome. The aim of the present investigation was to demonstrate that these mutations are necessary and sufficient for the development of the symptoms. We developed transgenic mice with a gain-of-function Epas1A529V mutation (corresponding to human EPAS1A530V), which demonstrated elevated levels of erythropoietin and polycythemia, a decreased urinary metanephrine-to-normetanephrine ratio, and increased expression of somatostatin in the ampullary region of duodenum. Further, inhibition of HIF2α with its specific inhibitor PT2385 significantly reduced erythropoietin levels in the mutant mice. However, polycythemia persisted after PT2385 treatment, suggesting an alternative erythropoietin-independent mechanism of polycythemia. These findings demonstrate the vital roles of EPAS1 mutations in the syndrome development and the great potential of the Epas1A529V animal model for further pathogenesis and therapeutics studies.

Specific genetic variants in the mitochondrially encoded 12S ribosomal RNA gene (MT-RNR1) cause aminoglycoside-induced irreversible hearing loss. Mitochondrial DNA is usually not included in targeted sequencing experiments; however, off-target data may deliver this information. Here, we extract MT-RNR1 genetic variation, including the most relevant ototoxicity variant m.1555A>G, using the off-target reads of 473 research samples, sequenced through a capture-based, custom-targeted panel and whole exome sequencing (WES), and of 1245 diagnostic samples with clinical WES. Sanger sequencing and fluorescence-based genotyping were used for genotype validation. There was a correlation between off-target reads and mitochondrial coverage (rcustomPanel = 0.39, p = 2 × 10-13 and rWES = 0.67, p = 7 × 10-21). The median read depth of MT-RNR1 m.1555 was similar to the average mitochondrial genome coverage, with saliva and blood samples giving comparable results. The genotypes from 415 samples, including three m.1555G carriers, were concordant with fluorescence-based genotyping data. In clinical WES, median MT-RNR1 coverage was 56×, with 90% of samples having ≥20 reads at m.1555 position, and one m.1494T and three m.1555G carriers were identified with no evidence for heteroplasmy. Altogether, this study shows that obtaining MT-RNR1 genotypes through off-target reads is an efficient strategy that can impulse preemptive pharmacogenetic screening of this mitochondrial gene.