Pheochromocytoma/Paraganglioma: A Poster Child for Cancer Metabolism

Metabolomics and proteomics in pheochromocytoma and paraganglioma: Translating biochemistry and biology to bedside

The complexity of omes - the key cellular ensembles (genome and epigenome, transcriptome, proteome, and metabolome) - is becoming increasingly understood in terms of big-data analysis, the omics. Amongst these, proteomics provides a global description of quantitative and qualitative alterations of protein expression (or protein abundance in body fluids) in response to physiologic or pathologic processes while metabolomics offers a functional portrait of the physiological state by quantifying metabolite abundances in biological samples. Here, we summarize how different techniques of proteomic and metabolic analysis can be used to define key biochemical characteristics of pheochromocytomas/paragangliomas (PPGL). The significance of omics in understanding features of PPGL biology that might translate to improved diagnosis and treatment will be highlighted.

Subclinical paraganglioma of the retroperitoneum: A case report

BACKGROUND

Paraganglioma (PGL) located in the retroperitoneum presents challenges in diagnosis and treatment due to its hidden location, lack of specific symptoms in the early stages, and absence of distinctive manifestations on imaging.

CASE SUMMARY

A 56-year-old woman presented with a left upper abdominal mass discovered 1 wk ago during a physical examination. She did not have a history of smoking, alcohol consumption, or other harmful habits, no surgical procedures or infectious diseases, and had a 4-year history of hypertension. Upon admission, she did not exhibit fever, vomiting, or abdominal distension. Physical examination indicated mild percussion pain in the left upper abdomen, with no palpable enlargement of the liver or spleen. Laboratory tests and tumor markers showed no significant abnormalities. Enhanced computed tomography and magnetic resonance imaging of the upper abdomen revealed a cystic solid mass in the left epigastrium measuring approximately 6.5 cm × 4.5 cm, with inhomogeneous enhancement in the arterial phase, closely associated with the lesser curvature of the stomach and the pancreas. The patient underwent laparoscopic resection of the retroperitoneal mass, which was successfully removed without tumor rupture. A 12-month postoperative follow-up period showed good recovery.

CONCLUSION

This case report details the successful laparoscopic resection of a retroperitoneal subclinical PGL, resulting in a good recovery observed at the 12-month follow-up. Interestingly, the patient also experienced unexpected cure of hypertensive disease.

Vagal paragangliomas

PURPOSE OF REVIEW

A vagal paraganglioma is a rare head and neck tumor arising from the paraganglionic tissue within the perineurium of the vagus nerve, anywhere along the course of the nerve. Due to its proximity to the internal carotid artery, the internal jugular vein and the lower cranial nerves, this disorder poses significant diagnostic and therapeutic challenges. The diagnostic workup and management keep on evolving.

RECENT FINDINGS

This article gives a concise update of the clinical spectrum and the current state-of-the-art diagnostic workup and management of vagal paraganglioma.

SUMMARY

Every patient with suspected vagal paraganglioma needs to be evaluated by a multidisciplinary team. The management strategy is selected depending on the growth rate of the tumor, the age and fitness of the patient, the number of affected cranial nerves, the metabolic activity of the paraganglioma, and the eventual multicentricity. An algorithm guiding the clinician through the different treatment options is presented.

Head and Neck Paragangliomas: An Update on the Molecular Classification, State-of-the-Art Imaging, and Management Recommendations

Paragangliomas are neuroendocrine tumors that derive from paraganglia of the autonomic nervous system, with the majority of parasympathetic paragangliomas arising in the head and neck. More than one-third of all paragangliomas are hereditary, reflecting the strong genetic predisposition of these tumors. The molecular basis of paragangliomas has been investigated extensively in the past couple of decades, leading to the discovery of several molecular clusters and more than 20 well-characterized driver genes (somatic and hereditary), which are more than are known for any other endocrine tumor. Head and neck paragangliomas are largely related to the pseudohypoxia cluster and have been previously excluded from most molecular profiling studies. This review article introduces the molecular classification of paragangliomas, with a focus on head and neck paragangliomas, and discusses its impact on the management of these tumors. Genetic testing is now recommended for all patients with paragangliomas to provide screening and surveillance recommendations for patients and relatives. While CT and MRI provide excellent anatomic characterization of paragangliomas, gallium 68 tetraazacyclododecane tetraacetic acid-octreotate (ie, ⁶⁸Ga-DOTATATE) has superior sensitivity and is recommended as first-line imaging in patients with head and neck paragangliomas with concern for multifocal and metastatic disease, patients with known multifocal and metastatic disease, and in candidates for targeted peptide-receptor therapy. Keywords: Molecular Imaging, MR Perfusion, MR Spectroscopy, Neuro-Oncology, PET/CT, SPECT/CT, Head/Neck, Genetic Defects © RSNA, 2022.

Case report: Two sisters with a germline CHEK2 variant and distinct endocrine neoplasias

Genetic testing has become the standard of care for many disease states. As a result, physicians treating patients who have tumors often rely on germline genetic testing results for making clinical decisions. Cases of two sisters carrying a germline CHEK2 variant are highlighted whereby possible other genetic drivers were discovered on tumor analysis. CHEK2 (also referred to as CHK2) loss of function has been firmly associated with breast cancer development. In this case report, two siblings with a germline CHEK2 mutation also had distinct endocrine tumors. Pituitary adenoma and pancreatic neuroendocrine tumor (PNET) was found in the first sibling and pheochromocytoma (PCC) discovered in the second sibling. Although pituitary adenomas, PNETs, and PCC have been associated with NF1 gene mutations, the second sister with a PCC did have proven germline CHEK2 with a pathogenic somatic NF1 mutation. We highlight the clinical point that unless the tumor is sequenced, the real driver mutation that is causing the patient's tumor may remain unknown.

Targeting pheochromocytoma/paraganglioma with polyamine inhibitors

BACKGROUND

Pheochromocytomas (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.

METHODS

Metabolomic 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.

RESULTS

Components 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.

CONCLUSIONS

This 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.

Novel methods in adrenal research: a metabolomics approach

Metabolic alterations have implications in a spectrum of tissue functions and disease. Aided by novel molecular biological and computational tools, our understanding of physiological and pathological processes underpinning endocrine and endocrine-related disease has significantly expanded over the last decade. Herein, we focus on novel metabolomics-related methodologies in adrenal research: in situ metabolomics by mass spectrometry imaging, steroid metabolomics by gas and liquid chromatography-mass spectrometry, energy pathway metabologenomics by liquid chromatography-mass spectrometry-based metabolomics of Krebs cycle intermediates, and cellular reprogramming to generate functional steroidogenic cells and hence to modulate the steroid metabolome. All four techniques to assess and/or modulate the metabolome in biological systems provide tremendous opportunities to manage neoplastic and non-neoplastic disease of the adrenal glands in the era of precision medicine. In this context, we discuss emerging clinical applications and/or promising metabolic-driven research towards diagnostic, prognostic, predictive and therapeutic biomarkers in tumours arising from the adrenal gland and extra-adrenal paraganglia as well as modern approaches to delineate and reprogram adrenal metabolism.